Systems and methods for configuring flow control of policy expressions

ABSTRACT

Systems and methods for configuring and evaluating policies that direct processing of one or more data streams are described. A configuration interface is described for allowing users to specify object oriented policies. These object oriented policies may allow any data structures to be applied with respect to a payload of a received packet stream, including any portions of HTTP traffic. A configuration interface may also allow the user to control the order in which policies and policy groups are executed, in addition to specifying actions to be taken if one or more policies are undefined. Systems and methods for processing the policies may allow efficient processing of object-oriented policies by applying potentially complex data structures to unstructured data streams. A device may also interpret and process a number of flow control commands and policy group invocation statements to determine an order of execution among a number of policies and policy groups. These policy configurations and processing may allow configuration and processing of complex network behaviors relating to load balancing, VPNs, SSL offloading, content switching, application security, acceleration, and caching.

FIELD OF THE INVENTION

The present invention relates to computer networking technologies.Specifically, the present invention relates to systems and methods forconfiguring and applying policies and settings in network devices.

BACKGROUND OF THE INVENTION

Network devices and clients may provide a number of complex functionswith respect to network traffic. Among other functions, network devicesmay provide load balancing, application security, content switching, SSLoffloading, acceleration, and caching. However, as the number andcomplexity of the functions provided by network devices grows, thecomplexity and amount of configuration required for a network device maysimilarly increase. Further, improper or suboptimal configuration of anetwork device may result in decreased performance, network errors,application incompatibility, and weakened security.

Many network devices may utilize a policy framework to control networkdevice functions. In these frameworks, a policy may specify a rule andan action which dictates a behavior under certain conditions. Forexample, with HTTP traffic, a policy framework may allow a user toconfigure device behavior based on content within the HTTP stream. Thesepolicies may become complex depending on the content to be analyzed andthe behaviors sought. Thus, there exists a need for a policy frameworkwhich allows a user to apply structure to network traffic for thepurpose of writing policies to direct device behavior. There similarlyexists a need for a network device which can then implement suchstructured policy expressions in an efficient manner.

In addition, as the number and complexity of network device functionsgrow, the number of policies required for their configuration may alsogrow. With an increase in the number of policies, there also exists aneed for specifying and implementing processing orders among policiesand groups of policies.

Further, some desirable policies used in network devices may not alwayshave defined results. For example, a policy may specify behavior inresponse to a given field of an HTTP request, but may be undefined incases where the field is not present or the field has an unexpectedvalue. While it may be possible in some cases to write policies that arealways defined, this may require additional policies or more complexpolicies and may increase administrative overhead. Thus, there exists aneed for configuration systems which allow a user to specify one or moreactions for the case in which a policy is undefined.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed towards systems and methods forconfiguring and evaluating policies that direct processing of one ormore data streams. A configuration interface is described for allowingusers to specify object oriented policies. These object orientedpolicies may allow any data structures to be applied with respect to apayload of a received packet stream, including any portions of HTTPtraffic. A configuration interface may also allow the user to controlthe order in which policies and policy groups are executed, in additionto specifying actions to be taken if one or more policies are undefined.Systems and methods for processing the policies may allow efficientprocessing of object-oriented policies by applying potentially complexdata structures to unstructured data streams. A device may alsointerpret and process a number of flow control commands and policy groupinvocation statements to determine an order of execution among a numberof policies and policy groups. These policy configurations andprocessing may allow a user to efficiently configure complex networkbehaviors relating to load balancing, VPNs, SSL offloading, contentswitching, application security, acceleration, and caching.

In one aspect, the present invention relates to systems and methods ofconfiguring a policy of a network device with an object-orientedexpression to specify structure in a payload of a packet stream receivedby a network device In one embodiment, the method comprises: providing aconfiguration interface for configuring a policy for a network device;receiving, via the configuration interface, an expression for thepolicy, the expression identifying (i) an object class to apply to aportion of the payload of a packet stream, and (ii) a member of theobject class; and receiving, via the configuration interface,information identifying an action for the policy, the action to be takenbased on an evaluation of the expression.

In a second aspect, the present invention relates to systems and methodsfor applying object-oriented expressions in a policy to specifystructure in a payload of a packet stream received by the appliance. Inone embodiment, a method comprises: identifying, by an appliance, apolicy to evaluate with respect to a payload of a received packetstream, the policy specifying (i) an object class to apply to a portionof the payload of a packet stream, (ii) a member of the object class and(iii) an action; selecting, by the appliance, a portion of the payloadidentified by the object class; determining, by the appliance, a valuefor the member of the object class; and taking, in response to thedetermined value, the action. In another embodiment, a method comprises:identifying, by an appliance, a policy comprising an object-orientedexpression to evaluate with respect to a payload of a received packetstream; assigning, by the appliance, values to a data structurespecified by the object-oriented expression based on a portion of thepayload; performing, by the appliance, an evaluation of the expressionbased on the assigned values; and taking, in response to the evaluation,an action specified by the policy. Corresponding systems may include apacket processor for receiving packet streams and a policy engine forevaluating one or more object-oriented policies and taking associatedactions.

In a third aspect, the present invention relates to systems and methodsfor applying object-oriented expressions in a policy to specifystructure in a payload of a packet stream received by the appliance. Inone embodiment, a method comprises: identifying, by an appliance, apolicy comprising an object-oriented expression to evaluate with respectto a payload of a received packet stream; assigning, by the appliance,values to a data structure specified by the object-oriented expressionbased on a portion of the payload; performing, by the appliance, anevaluation of the expression based on the assigned values; altering, inresponse to the evaluation, a portion of the received packet stream; andtransmitting, by the appliance, the altered packet stream. Correspondingsystems may include a packet processor for receiving and forwarding thepacket stream and a policy engine for evaluating one or moreobject-oriented policies and taking associated actions.

In a fourth aspect the present invention relates to systems and methodsfor configuring and/or processing a policy used by a network device byspecifying an action to be taken in the event an element of the policyis undefined. In one embodiment, a method comprises: providing aconfiguration interface for configuring a policy of a network device;identifying, by the configuration interface, a policy comprising a firstaction to be taken based on an evaluation of an expression; receiving,via the configuration interface, information identifying a second actionfor the policy, the second action to be taken if an element of thepolicy is undefined. In another embodiment, a method of applying apolicy specifying an action to be taken in the event an element of thepolicy is undefined comprises: identifying, by an appliance, a policy toevaluate with respect to a payload of a received packet stream, thepolicy specifying (i) an expression, (ii) a first action to be takenbased on an evaluation of the expression and (iii) a second action to betaken if an element of the policy is undefined; determining, by theappliance, an element of the policy is undefined with respect to thepayload; and taking, by the appliance in response to the determination,the second action. Corresponding systems may include a packet processorfor receiving a packet stream, and a policy engine for evaluating one ormore policies and taking associated actions.

In a fifth aspect, the present invention relates to systems and methodsfor configuring and/or processing flow control among policies used inprocessing a packet stream. In one embodiment, a method comprises:providing a configuration interface for configuring a plurality ofpolicies of a network device, at least one policy of the plurality ofpolicies comprising a policy identifier; and receiving, via theconfiguration interface, information identifying a first policy of theplurality of policies, the first policy identifying (i) a rulecomprising a first expression and (ii) a first action to be taken basedon an evaluation of the rule; and receiving, via the configurationinterface, information identifying a second policy of the plurality ofpolicies to apply subsequent to the first policy if the rule evaluatesto true. In another embodiment, a method includes: identifying, by anappliance, a plurality of policies to apply to a received packet stream,at least one policy of the plurality of policies comprising a policyidentifier; processing, by the appliance, a first policy of theplurality of policies, the first policy identifying (i) a rulecomprising a first expression and (ii) a first action to be taken basedon an evaluation of the rule, and (iii) a second policy of the pluralityof policies; determining, by the appliance based on an evaluation of theexpression, the rule evaluates to true; and processing, by the appliancein response to the determination, the identified second policy.Corresponding systems may include a packet processor for receiving apacket stream, and a policy engine for evaluating one or more policiesand taking associated actions.

In a sixth aspect, the present invention relates to systems and methodsfor configuring and/or processing flow control among policy groups usedin a network device processing a packet stream. In one embodiment, amethod comprises: providing a configuration interface for configuring aplurality of policy groups for a network device; identifying, by theconfiguration interface, a first policy of a first policy group, thefirst policy specifying a rule comprising a first expression; andreceiving, via the interface, information identifying a second policygroup to be processed based on an evaluation of the rule. In anotherembodiment, a method comprises: identifying, by an appliance, a firstpolicy group to apply to a received packet stream; processing, by theappliance, a first policy of the first policy group, the first policyidentifying (i) a rule comprising a first expression, and (ii)information identifying a second policy group; evaluating, by theappliance, the rule; and processing, by the appliance in response to theevaluation of the rule, the identified second policy group.Corresponding systems may include a packet processor for receiving apacket stream and a policy engine for evaluating one or more policiesand taking associated actions.

In a seventh aspect, the present invention relates to systems andmethods for configuring and/or processing one or more applicationsecurity profiles for a device, each application security profilespecifying a number of checks performing security functions related toan application. In one embodiment, a method comprises: providing aconfiguration interface for configuring an application security profile;receiving, via the configuration interface, a first setting, the settingspecifying corresponding to a first check of the application securityprofile; receiving, via the configuration interface, a second setting,the second setting specifying corresponding to a second check of theapplication security profile; identifying, by the configurationinterface, a policy, the policy specifying a rule comprising a firstexpression; and receiving, via the interface, information identifyingthe application security profile to be processed based on an evaluationof the rule. In another embodiment, a method may comprise identifying,by an appliance, a first policy to apply to a received packet stream;the first policy specifying a rule comprising a first expression andidentifying an application security profile; evaluating, by theappliance, the rule; processing, by the appliance in response to theevaluation of the rule, a first check specified by the applicationsecurity profile; and processing, by the appliance in response to theevaluation of the rule, a second check specified by the applicationsecurity profile. Corresponding systems may include a packet processorfor receiving a packet stream and a policy engine for evaluating one ormore application security profiles and taking associated actions.

The details of various embodiments of the invention are set forth in theaccompanying drawings and the description below.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing and other objects, aspects, features, and advantages ofthe invention will become more apparent and better understood byreferring to the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1A is a block diagram of an embodiment of a network environment fora client to access a server via an appliance;

FIG. 1B is a block diagram of another embodiment of a networkenvironment for delivering a computing environment from a server to aclient via a plurality of appliances;

FIG. 1C is a block diagram of another embodiment of a networkenvironment for delivering a computing environment from a server to aclient via one or more different appliances;

FIG. 1D is a block diagram of an embodiment of an environment fordelivering a computing environment from a server to a client via anetwork;

FIGS. 1E and 1F are block diagrams of embodiments of a computing device;

FIG. 2A is a block diagram of an embodiment of an appliance forprocessing communications between a client and a server;

FIG. 2B is a block diagram of another embodiment of an appliance foroptimizing, accelerating, load-balancing and routing communicationsbetween a client and a server;

FIG. 3 is a block diagram of an embodiment of a client for communicatingwith a server via the appliance;

FIG. 4A is a diagram of an example object model that may be used tostructure HTTP communications;

FIG. 4B is an example screen of documentation for an object model thatmay be used to structure HTTP communications;

FIG. 4C illustrates a number of example object-oriented expressionsrelating to HTTP communications;

FIG. 5 illustrates an example of a policy;

FIG. 6 is an example screen that may be used to configure one or moreexpressions;

FIG. 7A is an example screen of a configuration interface that may beused to configure policies for a network device;

FIG. 7B is a block diagram of one embodiment of a configurationinterface executing on a client;

FIG. 8A is a flow diagram of one embodiment of a method for configuringa policy expression;

FIG. 8B is a flow diagram of one embodiment of a method for processingan object-oriented expression in a network appliance;

FIG. 8C is a low diagram of one embodiment of a method for usingobject-oriented expressions to rewrite portions of a received packetstream;

FIG. 9 is a flow diagram of one embodiment of a method for handlingundefined policy elements;

FIG. 10A is a diagram of an example of one embodiment of a policy bank;

FIG. 10B is a flow diagram of one embodiment for controlling processingorder in a group of policies;

FIG. 11A is a block diagram of one embodiment of controlling processingorder among a plurality of policy groups.

FIG. 11B is a block diagram of one embodiment of a method of controllingprocessing order among a plurality of policy groups;

FIG. 12 illustrates a number of example configuration screens which maybe used to configure an application security profile;

FIG. 13A is a flow diagram of one embodiment of a method for configuringan application security profile; and

FIG. 13B is a flow diagram of one embodiment of a method for processingan application security profile.

The features and advantages of the present invention will become moreapparent from the detailed description set forth below when taken inconjunction with the drawings, in which like reference charactersidentify corresponding elements throughout. In the drawings, likereference numbers generally indicate identical, functionally similar,and/or structurally similar elements.

DETAILED DESCRIPTION OF THE INVENTION

For purposes of reading the description of the various embodiments ofthe present invention below, the following descriptions of the sectionsof the specification and their respective contents may be helpful:

-   -   Section A describes a network environment and computing        environment useful for practicing an embodiment of the present        invention;    -   Section B describes embodiments of a system and appliance        architecture for accelerating delivery of a computing        environment to a remote user;    -   Section C describes embodiments of a client agent for        accelerating communications between a client and a server;    -   Section D describes embodiments of systems and methods for        configuring and using object-oriented policy expressions;    -   Section E describes embodiments of systems and methods for        handling undefined policy expressions;    -   Section F describes embodiments of systems and methods for        configuring and using policy groups; and    -   Section G describes embodiments of systems and methods for        configuring and using application security profiles.        A. Network and Computing Environment

Prior to discussing the specifics of embodiments of the systems andmethods of an appliance and/or client, it may be helpful to discuss thenetwork and computing environments in which such embodiments may bedeployed. Referring now to FIG. 1A, an embodiment of a networkenvironment is depicted. In brief overview, the network environmentcomprises one or more clients 102 a-102 n (also generally referred to aslocal machine(s) 102, or client(s) 102) in communication with one ormore servers 106 a-106 n (also generally referred to as server(s) 106,or remote machine(s) 106) via one or more networks 104, 104′ (generallyreferred to as network 104). In some embodiments, a client 102communicates with a server 106 via an appliance 200.

Although FIG. 1A shows a network 104 and a network 104′ between theclients 102 and the servers 106, the clients 102 and the servers 106 maybe on the same network 104. The networks 104 and 104′ can be the sametype of network or different types of networks. The network 104 and/orthe network 104′ can be a local-area network (LAN), such as a companyIntranet, a metropolitan area network (MAN), or a wide area network(WAN), such as the Internet or the World Wide Web. In one embodiment,network 104′ may be a private network and network 104 may be a publicnetwork. In some embodiments, network 104 may be a private network andnetwork 104′ a public network. In another embodiment, networks 104 and104′ may both be private networks. In some embodiments, clients 102 maybe located at a branch office of a corporate enterprise communicatingvia a WAN connection over the network 104 to the servers 106 located ata corporate data center.

The network 104 and/or 104′ be any type and/or form of network and mayinclude any of the following: a point to point network, a broadcastnetwork, a wide area network, a local area network, a telecommunicationsnetwork, a data communication network, a computer network, an ATM(Asynchronous Transfer Mode) network, a SONET (Synchronous OpticalNetwork) network, a SDH (Synchronous Digital Hierarchy) network, awireless network and a wireline network. In some embodiments, thenetwork 104 may comprise a wireless link, such as an infrared channel orsatellite band. The topology of the network 104 and/or 104′ may be abus, star, or ring network topology. The network 104 and/or 104′ andnetwork topology may be of any such network or network topology as knownto those ordinarily skilled in the art capable of supporting theoperations described herein.

As shown in FIG. 1A, the appliance 200, which also may be referred to asan interface unit 200 or gateway 200, is shown between the networks 104and 104′. In some embodiments, the appliance 200 may be located onnetwork 104. For example, a branch office of a corporate enterprise maydeploy an appliance 200 at the branch office. In other embodiments, theappliance 200 may be located on network 104′. For example, an appliance200 may be located at a corporate data center. In yet anotherembodiment, a plurality of appliances 200 may be deployed on network104. In some embodiments, a plurality of appliances 200 may be deployedon network 104′. In one embodiment, a first appliance 200 communicateswith a second appliance 200′. In other embodiments, the appliance 200could be a part of any client 102 or server 106 on the same or differentnetwork 104,104′ as the client 102. One or more appliances 200 may belocated at any point in the network or network communications pathbetween a client 102 and a server 106.

In some embodiments, the appliance 200 comprises any of the networkdevices manufactured by Citrix Systems, Inc. of Ft. Lauderdale Fla.,referred to as Citrix NetScaler devices. In other embodiments, theappliance 200 includes any of the product embodiments referred to asWebAccelerator and BigIP manufactured by F5 Networks, Inc. of Seattle,Wash. In another embodiment, the appliance 205 includes any of the DXacceleration device platforms and/or the SSL VPN series of devices, suchas SA 700, SA 2000, SA 4000, and SA 6000 devices manufactured by JuniperNetworks, Inc. of Sunnyvale, Calif. In yet another embodiment, theappliance 200 includes any application acceleration and/or securityrelated appliances and/or software manufactured by Cisco Systems, Inc.of San Jose, Calif., such as the Cisco ACE Application Control EngineModule service software and network modules, and Cisco AVS SeriesApplication Velocity System.

In one embodiment, the system may include multiple, logically-groupedservers 106. In these embodiments, the logical group of servers may bereferred to as a server farm 38. In some of these embodiments, theserves 106 may be geographically dispersed. In some cases, a farm 38 maybe administered as a single entity. In other embodiments, the serverfarm 38 comprises a plurality of server farms 38. In one embodiment, theserver farm executes one or more applications on behalf of one or moreclients 102.

The servers 106 within each farm 38 can be heterogeneous. One or more ofthe servers 106 can operate according to one type of operating systemplatform (e.g., WINDOWS NT, manufactured by Microsoft Corp. of Redmond,Wash.), while one or more of the other servers 106 can operate onaccording to another type of operating system platform (e.g., Unix orLinux). The servers 106 of each farm 38 do not need to be physicallyproximate to another server 106 in the same farm 38. Thus, the group ofservers 106 logically grouped as a farm 38 may be interconnected using awide-area network (WAN) connection or medium-area network (MAN)connection. For example, a farm 38 may include servers 106 physicallylocated in different continents or different regions of a continent,country, state, city, campus, or room. Data transmission speeds betweenservers 106 in the farm 38 can be increased if the servers 106 areconnected using a local-area network (LAN) connection or some form ofdirect connection.

Servers 106 may be referred to as a file server, application server, webserver, proxy server, or gateway server. In some embodiments, a server106 may have the capacity to function as either an application server oras a master application server. In one embodiment, a server 106 mayinclude an Active Directory. The clients 102 may also be referred to asclient nodes or endpoints. In some embodiments, a client 102 has thecapacity to function as both a client node seeking access toapplications on a server and as an application server providing accessto hosted applications for other clients 102 a-102 n.

In some embodiments, a client 102 communicates with a server 106. In oneembodiment, the client 102 communicates directly with one of the servers106 in a farm 38. In another embodiment, the client 102 executes aprogram neighborhood application to communicate with a server 106 in afarm 38. In still another embodiment, the server 106 provides thefunctionality of a master node. In some embodiments, the client 102communicates with the server 106 in the farm 38 through a network 104.Over the network 104, the client 102 can, for example, request executionof various applications hosted by the servers 106 a-106 n in the farm 38and receive output of the results of the application execution fordisplay. In some embodiments, only the master node provides thefunctionality required to identify and provide address informationassociated with a server 106′ hosting a requested application.

In one embodiment, the server 106 provides functionality of a webserver. In another embodiment, the server 106 a receives requests fromthe client 102, forwards the requests to a second server 106 b andresponds to the request by the client 102 with a response to the requestfrom the server 106 b. In still another embodiment, the server 106acquires an enumeration of applications available to the client 102 andaddress information associated with a server 106 hosting an applicationidentified by the enumeration of applications. In yet anotherembodiment, the server 106 presents the response to the request to theclient 102 using a web interface. In one embodiment, the client 102communicates directly with the server 106 to access the identifiedapplication. In another embodiment, the client 102 receives applicationoutput data, such as display data, generated by an execution of theidentified application on the server 106.

Referring now to FIG. 1B, an embodiment of a network environmentdeploying multiple appliances 200 is depicted. A first appliance 200 maybe deployed on a first network 104 and a second appliance 200′ on asecond network 104′. For example a corporate enterprise may deploy afirst appliance 200 at a branch office and a second appliance 200′ at adata center. In another embodiment, the first appliance 200 and secondappliance 200′ are deployed on the same network 104 or network 104. Forexample, a first appliance 200 may be deployed for a first server farm38, and a second appliance 200 may be deployed for a second server farm38′. In another example, a first appliance 200 may be deployed at afirst branch office while the second appliance 200′ is deployed at asecond branch office. In some embodiments, the first appliance 200 andsecond appliance 200′ work in cooperation or in conjunction with eachother to accelerate network traffic or the delivery of application anddata between a client and a server

Referring now to FIG. 1C, another embodiment of a network environmentdeploying the appliance 200 with one or more other types of appliances,such as between one or more WAN optimization appliance 205, 205′ isdepicted. For example a first WAN optimization appliance 205 is shownbetween networks 104 and 104′ and s second WAN optimization appliance205′ may be deployed between the appliance 200 and one or more servers106. By way of example, a corporate enterprise may deploy a first WANoptimization appliance 205 at a branch office and a second WANoptimization appliance 205′ at a data center. In some embodiments, theappliance 205 may be located on network 104′. In other embodiments, theappliance 205′ may be located on network 104. In some embodiments, theappliance 205′ may be located on network 104′ or network 104″. In oneembodiment, the appliance 205 and 205′ are on the same network. Inanother embodiment, the appliance 205 and 205′ are on differentnetworks. In another example, a first WAN optimization appliance 205 maybe deployed for a first server farm 38 and a second WAN optimizationappliance 205′ for a second server farm 38′

In one embodiment, the appliance 205 is a device for accelerating,optimizing or otherwise improving the performance, operation, or qualityof service of any type and form of network traffic, such as traffic toand/or from a WAN connection. In some embodiments, the appliance 205 isa performance enhancing proxy. In other embodiments, the appliance 205is any type and form of WAN optimization or acceleration device,sometimes also referred to as a WAN optimization controller. In oneembodiment, the appliance 205 is any of the product embodiments referredto as WANScaler manufactured by Citrix Systems, Inc. of Ft. Lauderdale,Fla. In other embodiments, the appliance 205 includes any of the productembodiments referred to as BIG-IP link controller and WANjetmanufactured by F5 Networks, Inc. of Seattle, Wash. In anotherembodiment, the appliance 205 includes any of the WX and WXC WANacceleration device platforms manufactured by Juniper Networks, Inc. ofSunnyvale, Calif. In some embodiments, the appliance 205 includes any ofthe steelhead line of WAN optimization appliances manufactured byRiverbed Technology of San Francisco, Calif. In other embodiments, theappliance 205 includes any of the WAN related devices manufactured byExpand Networks Inc. of Roseland, N.J. In one embodiment, the appliance205 includes any of the WAN related appliances manufactured by PacketeerInc. of Cupertino, Calif., such as the PacketShaper, iShared, and SkyXproduct embodiments provided by Packeteer. In yet another embodiment,the appliance 205 includes any WAN related appliances and/or softwaremanufactured by Cisco Systems, Inc. of San Jose, Calif., such as theCisco Wide Area Network Application Services software and networkmodules, and Wide Area Network engine appliances.

In one embodiment, the appliance 205 provides application and dataacceleration services for branch-office or remote offices. In oneembodiment, the appliance 205 includes optimization of Wide Area FileServices (WAFS). In another embodiment, the appliance 205 acceleratesthe delivery of files, such as via the Common Internet File System(CIFS) protocol. In other embodiments, the appliance 205 providescaching in memory and/or storage to accelerate delivery of applicationsand data. In one embodiment, the appliance 205 provides compression ofnetwork traffic at any level of the network stack or at any protocol ornetwork layer. In another embodiment, the appliance 205 providestransport layer protocol optimizations, flow control, performanceenhancements or modifications and/or management to accelerate deliveryof applications and data over a WAN connection. For example, in oneembodiment, the appliance 205 provides Transport Control Protocol (TCP)optimizations. In other embodiments, the appliance 205 providesoptimizations, flow control, performance enhancements or modificationsand/or management for any session or application layer protocol.

In another embodiment, the appliance 205 encoded any type and form ofdata or information into custom or standard TCP and/or IP header fieldsor option fields of network packet to announce presence, functionalityor capability to another appliance 205′. In another embodiment, anappliance 205′ may communicate with another appliance 205′ using dataencoded in both TCP and/or IP header fields or options. For example, theappliance may use TCP option(s) or IP header fields or options tocommunicate one or more parameters to be used by the appliances 205,205′ in performing functionality, such as WAN acceleration, or forworking in conjunction with each other.

In some embodiments, the appliance 200 preserves any of the informationencoded in TCP and/or IP header and/or option fields communicatedbetween appliances 205 and 205′. For example, the appliance 200 mayterminate a transport layer connection traversing the appliance 200,such as a transport layer connection from between a client and a servertraversing appliances 205 and 205′. In one embodiment, the appliance 200identifies and preserves any encoded information in a transport layerpacket transmitted by a first appliance 205 via a first transport layerconnection and communicates a transport layer packet with the encodedinformation to a second appliance 205′ via a second transport layerconnection.

Referring now to FIG. 1D, a network environment for delivering and/oroperating a computing environment on a client 102 is depicted. In someembodiments, a server 106 includes an application delivery system 190for delivering a computing environment or an application and/or datafile to one or more clients 102. In brief overview, a client 10 is incommunication with a server 106 via network 104, 104′ and appliance 200.For example, the client 102 may reside in a remote office of a company,e.g., a branch office, and the server 106 may reside at a corporate datacenter. The client 102 comprises a client agent 120, and a computingenvironment 15. The computing environment 15 may execute or operate anapplication that accesses, processes or uses a data file. The computingenvironment 15, application and/or data file may be delivered via theappliance 200 and/or the server 106.

In some embodiments, the appliance 200 accelerates delivery of acomputing environment 15, or any portion thereof, to a client 102. Inone embodiment, the appliance 200 accelerates the delivery of thecomputing environment 15 by the application delivery system 190. Forexample, the embodiments described herein may be used to acceleratedelivery of a streaming application and data file processable by theapplication from a central corporate data center to a remote userlocation, such as a branch office of the company. In another embodiment,the appliance 200 accelerates transport layer traffic between a client102 and a server 106. The appliance 200 may provide accelerationtechniques for accelerating any transport layer payload from a server106 to a client 102, such as: 1) transport layer connection pooling, 2)transport layer connection multiplexing, 3) transport control protocolbuffering, 4) compression and 5) caching. In some embodiments, theappliance 200 provides load balancing of servers 106 in responding torequests from clients 102. In other embodiments, the appliance 200 actsas a proxy or access server to provide access to the one or more servers106. In another embodiment, the appliance 200 provides a secure virtualprivate network connection from a first network 104 of the client 102 tothe second network 104′ of the server 106, such as an SSL VPNconnection. It yet other embodiments, the appliance 200 providesapplication firewall security, control and management of the connectionand communications between a client 102 and a server 106.

In some embodiments, the application delivery management system 190provides application delivery techniques to deliver a computingenvironment to a desktop of a user, remote or otherwise, based on aplurality of execution methods and based on any authentication andauthorization policies applied via a policy engine 195. With thesetechniques, a remote user may obtain a computing environment and accessto server stored applications and data files from any network connecteddevice 100. In one embodiment, the application delivery system 190 mayreside or execute on a server 106. In another embodiment, theapplication delivery system 190 may reside or execute on a plurality ofservers 106 a-106 n. In some embodiments, the application deliverysystem 190 may execute in a server farm 38. In one embodiment, theserver 106 executing the application delivery system 190 may also storeor provide the application and data file. In another embodiment, a firstset of one or more servers 106 may execute the application deliverysystem 190, and a different server 106 n may store or provide theapplication and data file. In some embodiments, each of the applicationdelivery system 190, the application, and data file may reside or belocated on different servers. In yet another embodiment, any portion ofthe application delivery system 190 may reside, execute or be stored onor distributed to the appliance 200, or a plurality of appliances.

The client 102 may include a computing environment 15 for executing anapplication that uses or processes a data file. The client 102 vianetworks 104, 104′ and appliance 200 may request an application and datafile from the server 106. In one embodiment, the appliance 200 mayforward a request from the client 102 to the server 106. For example,the client 102 may not have the application and data file stored oraccessible locally. In response to the request, the application deliverysystem 190 and/or server 106 may deliver the application and data fileto the client 102. For example, in one embodiment, the server 106 maytransmit the application as an application stream to operate incomputing environment 15 on client 102.

In some embodiments, the application delivery system 190 comprises anyportion of the Citrix Access Suite™ by Citrix Systems, Inc., such as theMetaFrame or Citrix Presentation Server™ and/or any of the Microsoft®Windows Terminal Services manufactured by the Microsoft Corporation. Inone embodiment, the application delivery system 190 may deliver one ormore applications to clients 102 or users via a remote-display protocolor otherwise via remote-based or server-based computing. In anotherembodiment, the application delivery system 190 may deliver one or moreapplications to clients or users via steaming of the application.

In one embodiment, the application delivery system 190 includes a policyengine 195 for controlling and managing the access to, selection ofapplication execution methods and the delivery of applications. In someembodiments, the policy engine 195 determines the one or moreapplications a user or client 102 may access. In another embodiment, thepolicy engine 195 determines how the application should be delivered tothe user or client 102, e.g., the method of execution. In someembodiments, the application delivery system 190 provides a plurality ofdelivery techniques from which to select a method of applicationexecution, such as a server-based computing, streaming or delivering theapplication locally to the client 120 for local execution.

In one embodiment, a client 102 requests execution of an applicationprogram and the application delivery system 190 comprising a server 106selects a method of executing the application program. In someembodiments, the server 106 receives credentials from the client 102. Inanother embodiment, the server 106 receives a request for an enumerationof available applications from the client 102. In one embodiment, inresponse to the request or receipt of credentials, the applicationdelivery system 190 enumerates a plurality of application programsavailable to the client 102. The application delivery system 190receives a request to execute an enumerated application. The applicationdelivery system 190 selects one of a predetermined number of methods forexecuting the enumerated application, for example, responsive to apolicy of a policy engine. The application delivery system 190 mayselect a method of execution of the application enabling the client 102to receive application-output data generated by execution of theapplication program on a server 106. The application delivery system 190may select a method of execution of the application enabling the localmachine 10 to execute the application program locally after retrieving aplurality of application files comprising the application. In yetanother embodiment, the application delivery system 190 may select amethod of execution of the application to stream the application via thenetwork 104 to the client 102.

A client 102 may execute, operate or otherwise provide an application,which can be any type and/or form of software, program, or executableinstructions such as any type and/or form of web browser, web-basedclient, client-server application, a thin-client computing client, anActiveX control, or a Java applet, or any other type and/or form ofexecutable instructions capable of executing on client 102. In someembodiments, the application may be a server-based or a remote-basedapplication executed on behalf of the client 102 on a server 106. In oneembodiments the server 106 may display output to the client 102 usingany thin-client or remote-display protocol, such as the IndependentComputing Architecture (ICA) protocol manufactured by Citrix Systems,Inc. of Ft. Lauderdale, Fla. or the Remote Desktop Protocol (RDP)manufactured by the Microsoft Corporation of Redmond, Wash. Theapplication can use any type of protocol and it can be, for example, anHTTP client, an FTP client, an Oscar client, or a Telnet client. Inother embodiments, the application comprises any type of softwarerelated to VoIP communications, such as a soft IP telephone. In furtherembodiments, the application comprises any application related toreal-time data communications, such as applications for streaming videoand/or audio.

In some embodiments, the server 106 or a server farm 38 may be runningone or more applications, such as an application providing a thin-clientcomputing or remote display presentation application. In one embodiment,the server 106 or server farm 38 executes as an application, any portionof the Citrix Access Suite™ by Citrix Systems, Inc., such as theMetaFrame or Citrix Presentation Server™, and/or any of the Microsoft®Windows Terminal Services manufactured by the Microsoft Corporation. Inone embodiment, the application is an ICA client, developed by CitrixSystems, Inc. of Fort Lauderdale, Fla. In other embodiments, theapplication includes a Remote Desktop (RDP) client, developed byMicrosoft Corporation of Redmond, Wash. Also, the server 106 may run anapplication, which for example, may be an application server providingemail services such as Microsoft Exchange manufactured by the MicrosoftCorporation of Redmond, Wash., a web or Internet server, or a desktopsharing server, or a collaboration server. In some embodiments, any ofthe applications may comprise any type of hosted service or products,such as GoToMeeting™ provided by Citrix Online Division, Inc. of SantaBarbara, Calif., WebEx™ provided by WebEx, Inc. of Santa Clara, Calif.,or Microsoft Office Live Meeting provided by Microsoft Corporation ofRedmond, Wash.

Still referring to FIG. 1D, an embodiment of the network environment mayinclude a monitoring server 106A. The monitoring server 106A may includeany type and form performance monitoring service 198. The performancemonitoring service 198 may include monitoring, measurement and/ormanagement software and/or hardware, including data collection,aggregation, analysis, management and reporting. In one embodiment, theperformance monitoring service 198 includes one or more monitoringagents 197. The monitoring agent 197 includes any software, hardware orcombination thereof for performing monitoring, measurement and datacollection activities on a device, such as a client 102, server 106 oran appliance 200, 205. In some embodiments, the monitoring agent 197includes any type and form of script, such as Visual Basic script, orJavascript. In one embodiment, the monitoring agent 197 executestransparently to any application and/or user of the device. In someembodiments, the monitoring agent 197 is installed and operatedunobtrusively to the application or client. In yet another embodiment,the monitoring agent 197 is installed and operated without anyinstrumentation for the application or device.

In some embodiments, the monitoring agent 197 monitors, measures andcollects data on a predetermined frequency. In other embodiments, themonitoring agent 197 monitors, measures and collects data based upondetection of any type and form of event. For example, the monitoringagent 197 may collect data upon detection of a request for a web page orreceipt of an HTTP response. In another example, the monitoring agent197 may collect data upon detection of any user input events, such as amouse click. The monitoring agent 197 may report or provide anymonitored, measured or collected data to the monitoring service 198. Inone embodiment, the monitoring agent 197 transmits information to themonitoring service 198 according to a schedule or a predeterminedfrequency. In another embodiment, the monitoring agent 197 transmitsinformation to the monitoring service 198 upon detection of an event.

In some embodiments, the monitoring service 198 and/or monitoring agent197 performs monitoring and performance measurement of any networkresource or network infrastructure element, such as a client, server,server farm, appliance 200, appliance 205, or network connection. In oneembodiment, the monitoring service 198 and/or monitoring agent 197performs monitoring and performance measurement of any transport layerconnection, such as a TCP or UDP connection. In another embodiment, themonitoring service 198 and/or monitoring agent 197 monitors and measuresnetwork latency. In yet one embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures bandwidth utilization.

In other embodiments, the monitoring service 198 and/or monitoring agent197 monitors and measures end-user response times. In some embodiments,the monitoring service 198 performs monitoring and performancemeasurement of an application. In another embodiment, the monitoringservice 198 and/or monitoring agent 197 performs monitoring andperformance measurement of any session or connection to the application.In one embodiment, the monitoring service 198 and/or monitoring agent197 monitors and measures performance of a browser. In anotherembodiment, the monitoring service 198 and/or monitoring agent 197monitors and measures performance of HTTP based transactions. In someembodiments, the monitoring service 198 and/or monitoring agent 197monitors and measures performance of a Voice over IP (VoIP) applicationor session. In other embodiments, the monitoring service 198 and/ormonitoring agent 197 monitors and measures performance of a remotedisplay protocol application, such as an ICA client or RDP client. Inyet another embodiment, the monitoring service 198 and/or monitoringagent 197 monitors and measures performance of any type and form ofstreaming media. In still a further embodiment, the monitoring service198 and/or monitoring agent 197 monitors and measures performance of ahosted application or a Software-As-A-Service (SaaS) delivery model.

In some embodiments, the monitoring service 198 and/or monitoring agent197 performs monitoring and performance measurement of one or moretransactions, requests or responses related to application. In otherembodiments, the monitoring service 198 and/or monitoring agent 197monitors and measures any portion of an application layer stack, such asany .NET or J2EE calls. In one embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures database or SQLtransactions. In yet another embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures any method, functionor application programming interface (API) call.

In one embodiment, the monitoring service 198 and/or monitoring agent197 performs monitoring and performance measurement of a delivery ofapplication and/or data from a server to a client via one or moreappliances, such as appliance 200 and/or appliance 205. In someembodiments, the monitoring service 198 and/or monitoring agent 197monitors and measures performance of delivery of a virtualizedapplication. In other embodiments, the monitoring service 198 and/ormonitoring agent 197 monitors and measures performance of delivery of astreaming application. In another embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures performance ofdelivery of a desktop application to a client and/or the execution ofthe desktop application on the client. In another embodiment, themonitoring service 198 and/or monitoring agent 197 monitors and measuresperformance of a client/server application.

In one embodiment, the monitoring service 198 and/or monitoring agent197 is designed and constructed to provide application performancemanagement for the application delivery system 190. For example, themonitoring service 198 and/or monitoring agent 197 may monitor, measureand manage the performance of the delivery of applications via theCitrix Presentation Server. In this example, the monitoring service 198and/or monitoring agent 197 monitors individual ICA sessions. Themonitoring service 198 and/or monitoring agent 197 may measure the totaland per session system resource usage, as well as application andnetworking performance. The monitoring service 198 and/or monitoringagent 197 may identify the active servers for a given user and/or usersession. In some embodiments, the monitoring service 198 and/ormonitoring agent 197 monitors back-end connections between theapplication delivery system 190 and an application and/or databaseserver. The monitoring service 198 and/or monitoring agent 197 maymeasure network latency, delay and volume per user-session or ICAsession.

In some embodiments, the monitoring service 198 and/or monitoring agent197 measures and monitors memory usage for the application deliverysystem 190, such as total memory usage, per user session and/or perprocess. In other embodiments, the monitoring service 198 and/ormonitoring agent 197 measures and monitors CPU usage the applicationdelivery system 190, such as total CPU usage, per user session and/orper process. In another embodiments, the monitoring service 198 and/ormonitoring agent 197 measures and monitors the time required to log-into an application, a server, or the application delivery system, such asCitrix Presentation Server. In one embodiment, the monitoring service198 and/or monitoring agent 197 measures and monitors the duration auser is logged into an application, a server, or the applicationdelivery system 190. In some embodiments, the monitoring service 198and/or monitoring agent 197 measures and monitors active and inactivesession counts for an application, server or application delivery systemsession. In yet another embodiment, the monitoring service 198 and/ormonitoring agent 197 measures and monitors user session latency.

In yet further embodiments, the monitoring service 198 and/or monitoringagent 197 measures and monitors measures and monitors any type and formof server metrics. In one embodiment, the monitoring service 198 and/ormonitoring agent 197 measures and monitors metrics related to systemmemory, CPU usage, and disk storage. In another embodiment, themonitoring service 198 and/or monitoring agent 197 measures and monitorsmetrics related to page faults, such as page faults per second. In otherembodiments, the monitoring service 198 and/or monitoring agent 197measures and monitors round-trip time metrics. In yet anotherembodiment, the monitoring service 198 and/or monitoring agent 197measures and monitors metrics related to application crashes, errorsand/or hangs.

In some embodiments, the monitoring service 198 and monitoring agent 198includes any of the product embodiments referred to as EdgeSightmanufactured by Citrix Systems, Inc. of Ft. Lauderdale, Fla. In anotherembodiment, the performance monitoring service 198 and/or monitoringagent 198 includes any portion of the product embodiments referred to asthe TrueView product suite manufactured by the Symphoniq Corporation ofPalo Alto, Calif. In one embodiment, the performance monitoring service198 and/or monitoring agent 198 includes any portion of the productembodiments referred to as the TeaLeaf CX product suite manufactured bythe TeaLeaf Technology Inc. of San Francisco, Calif. In otherembodiments, the performance monitoring service 198 and/or monitoringagent 198 includes any portion of the business service managementproducts, such as the BMC Performance Manager and Patrol products,manufactured by BMC Software, Inc. of Houston, Tex.

The client 102, server 106, and appliance 200 may be deployed as and/orexecuted on any type and form of computing device, such as a computer,network device or appliance capable of communicating on any type andform of network and performing the operations described herein. FIGS. 1Eand 1F depict block diagrams of a computing device 100 useful forpracticing an embodiment of the client 102, server 106 or appliance 200.As shown in FIGS. 1E and 1F, each computing device 100 includes acentral processing unit 101, and a main memory unit 122. As shown inFIG. 1E, a computing device 100 may include a visual display device 124,a keyboard 126 and/or a pointing device 127, such as a mouse. Eachcomputing device 100 may also include additional optional elements, suchas one or more input/output devices 130 a-130 b (generally referred tousing reference numeral 130), and a cache memory 140 in communicationwith the central processing unit 101.

The central processing unit 101 is any logic circuitry that responds toand processes instructions fetched from the main memory unit 122. Inmany embodiments, the central processing unit is provided by amicroprocessor unit, such as: those manufactured by Intel Corporation ofMountain View, Calif.; those manufactured by Motorola Corporation ofSchaumburg, Ill.; those manufactured by Transmeta Corporation of SantaClara, Calif.; the RS/6000 processor, those manufactured byInternational Business Machines of White Plains, N.Y.; or thosemanufactured by Advanced Micro Devices of Sunnyvale, Calif. Thecomputing device 100 may be based on any of these processors, or anyother processor capable of operating as described herein.

Main memory unit 122 may be one or more memory chips capable of storingdata and allowing any storage location to be directly accessed by themicroprocessor 101, such as Static random access memory (SRAM), BurstSRAM or SynchBurst SRAM (BSRAM), Dynamic random access memory (DRAM),Fast Page Mode DRAM (FPM DRAM), Enhanced DRAM (EDRAM), Extended DataOutput RAM (EDO RAM), Extended Data Output DRAM (EDO DRAM), BurstExtended Data Output DRAM (BEDO DRAM), Enhanced DRAM (EDRAM),synchronous DRAM (SDRAM), JEDEC SRAM, PC100 SDRAM, Double Data RateSDRAM (DDR SDRAM), Enhanced SDRAM (ESDRAM), SyncLink DRAM (SLDRAM),Direct Rambus DRAM (DRDRAM), or Ferroelectric RAM (FRAM). The mainmemory 122 may be based on any of the above described memory chips, orany other available memory chips capable of operating as describedherein. In the embodiment shown in FIG. 1E, the processor 101communicates with main memory 122 via a system bus 150 (described inmore detail below). FIG. 1E depicts an embodiment of a computing device100 in which the processor communicates directly with main memory 122via a memory port 103. For example, in FIG. 1F the main memory 122 maybe DRDRAM.

FIG. 1F depicts an embodiment in which the main processor 101communicates directly with cache memory 140 via a secondary bus,sometimes referred to as a backside bus. In other embodiments, the mainprocessor 101 communicates with cache memory 140 using the system bus150. Cache memory 140 typically has a faster response time than mainmemory 122 and is typically provided by SRAM, BSRAM, or EDRAM. In theembodiment shown in FIG. 1E, the processor 101 communicates with variousI/O devices 130 via a local system bus 150. Various busses may be usedto connect the central processing unit 101 to any of the I/O devices130, including a VESA VL bus, an ISA bus, an EISA bus, a MicroChannelArchitecture (MCA) bus, a PCI bus, a PCI-X bus, a PCI-Express bus, or aNuBus. For embodiments in which the I/O device is a video display 124,the processor 101 may use an Advanced Graphics Port (AGP) to communicatewith the display 124. FIG. 1F depicts an embodiment of a computer 100 inwhich the main processor 101 communicates directly with I/O device 130via HyperTransport, Rapid I/O, or InfiniBand. FIG. 1F also depicts anembodiment in which local busses and direct communication are mixed: theprocessor 101 communicates with I/O device 130 using a localinterconnect bus while communicating with I/O device 130 directly.

The computing device 100 may support any suitable installation device116, such as a floppy disk drive for receiving floppy disks such as3.5-inch, 5.25-inch disks or ZIP disks, a CD-ROM drive, a CD-R/RW drive,a DVD-ROM drive, tape drives of various formats, USB device, hard-driveor any other device suitable for installing software and programs suchas any client agent 120, or portion thereof. The computing device 100may further comprise a storage device 128, such as one or more hard diskdrives or redundant arrays of independent disks, for storing anoperating system and other related software, and for storing applicationsoftware programs such as any program related to the client agent 120.Optionally, any of the installation devices 116 could also be used asthe storage device 128. Additionally, the operating system and thesoftware can be run from a bootable medium, for example, a bootable CD,such as KNOPPIX®, a bootable CD for GNU/Linux that is available as aGNU/Linux distribution from knoppix.net.

Furthermore, the computing device 100 may include a network interface118 to interface to a Local Area Network (LAN), Wide Area Network (WAN)or the Internet through a variety of connections including, but notlimited to, standard telephone lines, LAN or WAN links (e.g., 802.11,T1, T3, 56 kb, X.25), broadband connections (e.g., ISDN, Frame Relay,ATM), wireless connections, or some combination of any or all of theabove. The network interface 118 may comprise a built-in networkadapter, network interface card, PCMCIA network card, card bus networkadapter, wireless network adapter, USB network adapter, modem or anyother device suitable for interfacing the computing device 100 to anytype of network capable of communication and performing the operationsdescribed herein. A wide variety of I/O devices 130 a-130 n may bepresent in the computing device 100. Input devices include keyboards,mice, trackpads, trackballs, microphones, and drawing tablets. Outputdevices include video displays, speakers, inkjet printers, laserprinters, and dye-sublimation printers. The I/O devices 130 may becontrolled by an I/O controller 123 as shown in FIG. 1E. The I/Ocontroller may control one or more I/O devices such as a keyboard 126and a pointing device 127, e.g., a mouse or optical pen. Furthermore, anI/O device may also provide storage 128 and/or an installation medium116 for the computing device 100. In still other embodiments, thecomputing device 100 may provide USB connections to receive handheld USBstorage devices such as the USB Flash Drive line of devices manufacturedby Twintech Industry, Inc. of Los Alamitos, Calif.

In some embodiments, the computing device 100 may comprise or beconnected to multiple display devices 124 a-124 n, which each may be ofthe same or different type and/or form. As such, any of the I/O devices130 a-130 n and/or the I/O controller 123 may comprise any type and/orform of suitable hardware, software, or combination of hardware andsoftware to support, enable or provide for the connection and use ofmultiple display devices 124 a-124 n by the computing device 100. Forexample, the computing device 100 may include any type and/or form ofvideo adapter, video card, driver, and/or library to interface,communicate, connect or otherwise use the display devices 124 a-124 n.In one embodiment, a video adapter may comprise multiple connectors tointerface to multiple display devices 124 a-124 n. In other embodiments,the computing device 100 may include multiple video adapters, with eachvideo adapter connected to one or more of the display devices 124 a-124n. In some embodiments, any portion of the operating system of thecomputing device 100 may be configured for using multiple displays 124a-124 n. In other embodiments, one or more of the display devices 124a-124 n may be provided by one or more other computing devices, such ascomputing devices 100 a and 100 b connected to the computing device 100,for example, via a network. These embodiments may include any type ofsoftware designed and constructed to use another computer's displaydevice as a second display device 124 a for the computing device 100.One ordinarily skilled in the art will recognize and appreciate thevarious ways and embodiments that a computing device 100 may beconfigured to have multiple display devices 124 a-124 n.

In further embodiments, an I/O device 130 may be a bridge 170 betweenthe system bus 150 and an external communication bus, such as a USB bus,an Apple Desktop Bus, an RS-232 serial connection, a SCSI bus, aFireWire bus, a FireWire 800 bus, an Ethernet bus, an AppleTalk bus, aGigabit Ethernet bus, an Asynchronous Transfer Mode bus, a HIPPI bus, aSuper HIPPI bus, a SerialPlus bus, a SCI/LAMP bus, a FibreChannel bus,or a Serial Attached small computer system interface bus.

A computing device 100 of the sort depicted in FIGS. 1E and 1F typicallyoperate under the control of operating systems, which control schedulingof tasks and access to system resources. The computing device 100 can berunning any operating system such as any of the versions of theMicrosoft® Windows operating systems, the different releases of the Unixand Linux operating systems, any version of the Mac OS® for Macintoshcomputers, any embedded operating system, any real-time operatingsystem, any open source operating system, any proprietary operatingsystem, any operating systems for mobile computing devices, or any otheroperating system capable of running on the computing device andperforming the operations described herein. Typical operating systemsinclude: WINDOWS 3.x, WINDOWS 95, WINDOWS 98, WINDOWS 2000, WINDOWS NT3.51, WINDOWS NT 4.0, WINDOWS CE, and WINDOWS XP, all of which aremanufactured by Microsoft Corporation of Redmond, Wash.; MacOS,manufactured by Apple Computer of Cupertino, Calif.; OS/2, manufacturedby International Business Machines of Armonk, N.Y.; and Linux, afreely-available operating system distributed by Caldera Corp. of SaltLake City, Utah, or any type and/or form of a Unix operating system,among others.

In other embodiments, the computing device 100 may have differentprocessors, operating systems, and input devices consistent with thedevice. For example, in one embodiment the computer 100 is a Treo 180,270, 1060, 600 or 650 smart phone manufactured by Palm, Inc. In thisembodiment, the Treo smart phone is operated under the control of thePalmOS operating system and includes a stylus input device as well as afive-way navigator device. Moreover, the computing device 100 can be anyworkstation, desktop computer, laptop or notebook computer, server,handheld computer, mobile telephone, any other computer, or other formof computing or telecommunications device that is capable ofcommunication and that has sufficient processor power and memorycapacity to perform the operations described herein.

B. Appliance Architecture

FIG. 2A illustrates an example embodiment of the appliance 200. Thearchitecture of the appliance 200 in FIG. 2A is provided by way ofillustration only and is not intended to be limiting. As shown in FIG.2, appliance 200 comprises a hardware layer 206 and a software layerdivided into a user space 202 and a kernel space 204.

Hardware layer 206 provides the hardware elements upon which programsand services within kernel space 204 and user space 202 are executed.Hardware layer 206 also provides the structures and elements which allowprograms and services within kernel space 204 and user space 202 tocommunicate data both internally and externally with respect toappliance 200. As shown in FIG. 2, the hardware layer 206 includes aprocessing unit 262 for executing software programs and services, amemory 264 for storing software and data, network ports 266 fortransmitting and receiving data over a network, and an encryptionprocessor 260 for performing functions related to Secure Sockets Layerprocessing of data transmitted and received over the network. In someembodiments, the central processing unit 262 may perform the functionsof the encryption processor 260 in a single processor. Additionally, thehardware layer 206 may comprise multiple processors for each of theprocessing unit 262 and the encryption processor 260. The processor 262may include any of the processors 101 described above in connection withFIGS. 1E and 1F. In some embodiments, the central processing unit 262may perform the functions of the encryption processor 260 in a singleprocessor. Additionally, the hardware layer 206 may comprise multipleprocessors for each of the processing unit 262 and the encryptionprocessor 260. For example, in one embodiment, the appliance 200comprises a first processor 262 and a second processor 262′. In otherembodiments, the processor 262 or 262′ comprises a multi-core processor.

Although the hardware layer 206 of appliance 200 is generallyillustrated with an encryption processor 260, processor 260 may be aprocessor for performing functions related to any encryption protocol,such as the Secure Socket Layer (SSL) or Transport Layer Security (TLS)protocol. In some embodiments, the processor 260 may be a generalpurpose processor (GPP), and in further embodiments, may be haveexecutable instructions for performing processing of any securityrelated protocol.

Although the hardware layer 206 of appliance 200 is illustrated withcertain elements in FIG. 2, the hardware portions or components ofappliance 200 may comprise any type and form of elements, hardware orsoftware, of a computing device, such as the computing device 100illustrated and discussed herein in conjunction with FIGS. 1E and 1F. Insome embodiments, the appliance 200 may comprise a server, gateway,router, switch, bridge or other type of computing or network device, andhave any hardware and/or software elements associated therewith.

The operating system of appliance 200 allocates, manages, or otherwisesegregates the available system memory into kernel space 204 and userspace 204. In example software architecture 200, the operating systemmay be any type and/or form of Unix operating system although theinvention is not so limited. As such, the appliance 200 can be runningany operating system such as any of the versions of the Microsoft®Windows operating systems, the different releases of the Unix and Linuxoperating systems, any version of the Mac OS® for Macintosh computers,any embedded operating system, any network operating system, anyreal-time operating system, any open source operating system, anyproprietary operating system, any operating systems for mobile computingdevices or network devices, or any other operating system capable ofrunning on the appliance 200 and performing the operations describedherein.

The kernel space 204 is reserved for running the kernel 230, includingany device drivers, kernel extensions or other kernel related software.As known to those skilled in the art, the kernel 230 is the core of theoperating system, and provides access, control, and management ofresources and hardware-related elements of the application 104. Inaccordance with an embodiment of the appliance 200, the kernel space 204also includes a number of network services or processes working inconjunction with a cache manager 232, sometimes also referred to as theintegrated cache, the benefits of which are described in detail furtherherein. Additionally, the embodiment of the kernel 230 will depend onthe embodiment of the operating system installed, configured, orotherwise used by the device 200.

In one embodiment, the device 200 comprises one network stack 267, suchas a TCP/IP based stack, for communicating with the client 102 and/orthe server 106. In one embodiment, the network stack 267 is used tocommunicate with a first network, such as network 108, and a secondnetwork 110. In some embodiments, the device 200 terminates a firsttransport layer connection, such as a TCP connection of a client 102,and establishes a second transport layer connection to a server 106 foruse by the client 102, e.g., the second transport layer connection isterminated at the appliance 200 and the server 106. The first and secondtransport layer connections may be established via a single networkstack 267. In other embodiments, the device 200 may comprise multiplenetwork stacks, for example 267 and 267′, and the first transport layerconnection may be established or terminated at one network stack 267,and the second transport layer connection on the second network stack267′. For example, one network stack may be for receiving andtransmitting network packet on a first network, and another networkstack for receiving and transmitting network packets on a secondnetwork. In one embodiment, the network stack 267 comprises a buffer 243for queuing one or more network packets for transmission by theappliance 200.

As shown in FIG. 2, the kernel space 204 includes the cache manager 232,a high-speed layer 2-7 integrated packet engine 240, an encryptionengine 234, a policy engine 236 and multi-protocol compression logic238. Running these components or processes 232, 240, 234, 236 and 238 inkernel space 204 or kernel mode instead of the user space 202 improvesthe performance of each of these components, alone and in combination.Kernel operation means that these components or processes 232, 240, 234,236 and 238 run in the core address space of the operating system of thedevice 200. For example, running the encryption engine 234 in kernelmode improves encryption performance by moving encryption and decryptionoperations to the kernel, thereby reducing the number of transitionsbetween the memory space or a kernel thread in kernel mode and thememory space or a thread in user mode. For example, data obtained inkernel mode may not need to be passed or copied to a process or threadrunning in user mode, such as from a kernel level data structure to auser level data structure. In another aspect, the number of contextswitches between kernel mode and user mode are also reduced.Additionally, synchronization of and communications between any of thecomponents or processes 232, 240, 235, 236 and 238 can be performed moreefficiently in the kernel space 204.

In some embodiments, any portion of the components 232, 240, 234, 236and 238 may run or operate in the kernel space 204, while other portionsof these components 232, 240, 234, 236 and 238 may run or operate inuser space 202. In one embodiment, the appliance 200 uses a kernel-leveldata structure providing access to any portion of one or more networkpackets, for example, a network packet comprising a request from aclient 102 or a response from a server 106. In some embodiments, thekernel-level data structure may be obtained by the packet engine 240 viaa transport layer driver interface or filter to the network stack 267.The kernel-level data structure may comprise any interface and/or dataaccessible via the kernel space 204 related to the network stack 267,network traffic or packets received or transmitted by the network stack267. In other embodiments, the kernel-level data structure may be usedby any of the components or processes 232, 240, 234, 236 and 238 toperform the desired operation of the component or process. In oneembodiment, a component 232, 240, 234, 236 and 238 is running in kernelmode 204 when using the kernel-level data structure, while in anotherembodiment, the component 232, 240, 234, 236 and 238 is running in usermode when using the kernel-level data structure. In some embodiments,the kernel-level data structure may be copied or passed to a secondkernel-level data structure, or any desired user-level data structure.

The cache manager 232 may comprise software, hardware or any combinationof software and hardware to provide cache access, control and managementof any type and form of content, such as objects or dynamicallygenerated objects served by the originating servers 106. The data,objects or content processed and stored by the cache manager 232 maycomprise data in any format, such as a markup language, or communicatedvia any protocol. In some embodiments, the cache manager 232 duplicatesoriginal data stored elsewhere or data previously computed, generated ortransmitted, in which the original data may require longer access timeto fetch, compute or otherwise obtain relative to reading a cache memoryelement. Once the data is stored in the cache memory element, future usecan be made by accessing the cached copy rather than refetching orrecomputing the original data, thereby reducing the access time. In someembodiments, the cache memory element that comprise a data object inmemory 264 of device 200. In other embodiments, the cache memory elementmay comprise memory having a faster access time than memory 264. Inanother embodiment, the cache memory element may comprise any type andform of storage element of the device 200, such as a portion of a harddisk. In some embodiments, the processing unit 262 may provide cachememory for use by the cache manager 232. In yet further embodiments, thecache manager 232 may use any portion and combination of memory,storage, or the processing unit for caching data, objects, and othercontent.

Furthermore, the cache manager 232 includes any logic, functions, rules,or operations to perform any embodiments of the techniques of theappliance 200 described herein. For example, the cache manager 232includes logic or functionality to invalidate objects based on theexpiration of an invalidation time period or upon receipt of aninvalidation command from a client 102 or server 106. In someembodiments, the cache manager 232 may operate as a program, service,process or task executing in the kernel space 204, and in otherembodiments, in the user space 202. In one embodiment, a first portionof the cache manager 232 executes in the user space 202 while a secondportion executes in the kernel space 204. In some embodiments, the cachemanager 232 can comprise any type of general purpose processor (GPP), orany other type of integrated circuit, such as a Field Programmable GateArray (FPGA), Programmable Logic Device (PLD), or Application SpecificIntegrated Circuit (ASIC).

The policy engine 236 may include, for example, an intelligentstatistical engine or other programmable application(s). In oneembodiment, the policy engine 236 provides a configuration mechanism toallow a user to identify, specify, define or configure a caching policy.Policy engine 236, in some embodiments, also has access to memory tosupport data structures such as lookup tables or hash tables to enableuser-selected caching policy decisions. In other embodiments, the policyengine 236 may comprise any logic, rules, functions or operations todetermine and provide access, control and management of objects, data orcontent being cached by the appliance 200 in addition to access, controland management of security, network traffic, network access, compressionor any other function or operation performed by the appliance 200.Further examples of specific caching policies are further describedherein.

In some embodiments, the policy engine 236 may provide a configurationmechanism to allow a user to identify, specify, define or configurepolicies directing behavior of any other components or functionality ofan appliance including, without limitation, the components described inFIG. 2B such as vServers 275, VPN functions 280, Intranet IP functions282, switching functions 284, DNS functions 286, acceleration functions288, application firewall functions 290, and monitoring agents 197. Inother embodiments, the policy engine 236 may check, evaluate, implement,or otherwise act in response to any configured policies, and may alsodirect the operation of one or more appliance functions in response to apolicy.

The encryption engine 234 comprises any logic, business rules, functionsor operations for handling the processing of any security relatedprotocol, such as SSL or TLS, or any function related thereto. Forexample, the encryption engine 234 encrypts and decrypts networkpackets, or any portion thereof, communicated via the appliance 200. Theencryption engine 234 may also setup or establish SSL or TLS connectionson behalf of the client 102 a-102 n, server 106 a-106 n, or appliance200. As such, the encryption engine 234 provides offloading andacceleration of SSL processing. In one embodiment, the encryption engine234 uses a tunneling protocol to provide a virtual private networkbetween a client 102 a-102 n and a server 106 a-106 n. In someembodiments, the encryption engine 234 is in communication with theEncryption processor 260. In other embodiments, the encryption engine234 comprises executable instructions running on the Encryptionprocessor 260.

The multi-protocol compression engine 238 comprises any logic, businessrules, function or operations for compressing one or more protocols of anetwork packet, such as any of the protocols used by the network stack267 of the device 200. In one embodiment, multi-protocol compressionengine 238 compresses bi-directionally between clients 102 a-102 n andservers 106 a-106 n any TCP/IP based protocol, including MessagingApplication Programming Interface (MAPI) (email), File Transfer Protocol(FTP), HyperText Transfer Protocol (HTTP), Common Internet File System(CIFS) protocol (file transfer), Independent Computing Architecture(ICA) protocol, Remote Desktop Protocol (RDP), Wireless ApplicationProtocol (WAP), Mobile IP protocol, and Voice Over IP (VoIP) protocol.In other embodiments, multi-protocol compression engine 238 providescompression of Hypertext Markup Language (HTML) based protocols and insome embodiments, provides compression of any markup languages, such asthe Extensible Markup Language (XML). In one embodiment, themulti-protocol compression engine 238 provides compression of anyhigh-performance protocol, such as any protocol designed for appliance200 to appliance 200 communications. In another embodiment, themulti-protocol compression engine 238 compresses any payload of or anycommunication using a modified transport control protocol, such asTransaction TCP (T/TCP), TCP with selection acknowledgements (TCP-SACK),TCP with large windows (TCP-LW), a congestion prediction protocol suchas the TCP-Vegas protocol, and a TCP spoofing protocol.

As such, the multi-protocol compression engine 238 acceleratesperformance for users accessing applications via desktop clients, e.g.,Microsoft Outlook and non-Web thin clients, such as any client launchedby popular enterprise applications like Oracle, SAP and Siebel, and evenmobile clients, such as the Pocket PC. In some embodiments, themulti-protocol compression engine 238 by executing in the kernel mode204 and integrating with packet processing engine 240 accessing thenetwork stack 267 is able to compress any of the protocols carried bythe TCP/IP protocol, such as any application layer protocol.

High speed layer 2-7 integrated packet engine 240, also generallyreferred to as a packet processing engine or packet engine, isresponsible for managing the kernel-level processing of packets receivedand transmitted by appliance 200 via network ports 266. The high speedlayer 2-7 integrated packet engine 240 may comprise a buffer for queuingone or more network packets during processing, such as for receipt of anetwork packet or transmission of a network packer. Additionally, thehigh speed layer 2-7 integrated packet engine 240 is in communicationwith one or more network stacks 267 to send and receive network packetsvia network ports 266. The high speed layer 2-7 integrated packet engine240 works in conjunction with encryption engine 234, cache manager 232,policy engine 236 and multi-protocol compression logic 238. Inparticular, encryption engine 234 is configured to perform SSLprocessing of packets, policy engine 236 is configured to performfunctions related to traffic management such as request-level contentswitching and request-level cache redirection, and multi-protocolcompression logic 238 is configured to perform functions related tocompression and decompression of data.

The high speed layer 2-7 integrated packet engine 240 includes a packetprocessing timer 242. In one embodiment, the packet processing timer 242provides one or more time intervals to trigger the processing ofincoming, i.e., received, or outgoing, i.e., transmitted, networkpackets. In some embodiments, the high speed layer 2-7 integrated packetengine 240 processes network packets responsive to the timer 242. Thepacket processing timer 242 provides any type and form of signal to thepacket engine 240 to notify, trigger, or communicate a time relatedevent, interval or occurrence. In many embodiments, the packetprocessing timer 242 operates in the order of milliseconds, such as forexample 100 ms, 50 ms or 25 ms. For example, in some embodiments, thepacket processing timer 242 provides time intervals or otherwise causesa network packet to be processed by the high speed layer 2-7 integratedpacket engine 240 at a 10 ms time interval, while in other embodiments,at a 5 ms time interval, and still yet in further embodiments, as shortas a 3, 2, or 1 ms time interval. The high speed layer 2-7 integratedpacket engine 240 may be interfaced, integrated or in communication withthe encryption engine 234, cache manager 232, policy engine 236 andmulti-protocol compression engine 238 during operation. As such, any ofthe logic, functions, or operations of the encryption engine 234, cachemanager 232, policy engine 236 and multi-protocol compression logic 238may be performed responsive to the packet processing timer 242 and/orthe packet engine 240. Therefore, any of the logic, functions, oroperations of the encryption engine 234, cache manager 232, policyengine 236 and multi-protocol compression logic 238 may be performed atthe granularity of time intervals provided via the packet processingtimer 242, for example, at a time interval of less than or equal to 10ms. For example, in one embodiment, the cache manager 232 may performinvalidation of any cached objects responsive to the high speed layer2-7 integrated packet engine 240 and/or the packet processing timer 242.In another embodiment, the expiry or invalidation time of a cachedobject can be set to the same order of granularity as the time intervalof the packet processing timer 242, such as at every 10 ms.

In contrast to kernel space 204, user space 202 is the memory area orportion of the operating system used by user mode applications orprograms otherwise running in user mode. A user mode application may notaccess kernel space 204 directly and uses service calls in order toaccess kernel services. As shown in FIG. 2, user space 202 of appliance200 includes a graphical user interface (GUI) 210, a command lineinterface (CLI) 212, shell services 214, health monitoring program 216,and daemon services 218. GUI 210 and CLI 212 provide a means by which asystem administrator or other user can interact with and control theoperation of appliance 200, such as via the operating system of theappliance 200 and either is user space 202 or kernel space 204. The GUI210 may be any type and form of graphical user interface and may bepresented via text, graphical or otherwise, by any type of program orapplication, such as a browser. The CLI 212 may be any type and form ofcommand line or text-based interface, such as a command line provided bythe operating system. For example, the CLI 212 may comprise a shell,which is a tool to enable users to interact with the operating system.In some embodiments, the CLI 212 may be provided via a bash, csh, tcsh,or ksh type shell. The shell services 214 comprises the programs,services, tasks, processes or executable instructions to supportinteraction with the appliance 200 or operating system by a user via theGUI 210 and/or CLI 212.

Health monitoring program 216 is used to monitor, check, report andensure that network systems are functioning properly and that users arereceiving requested content over a network. Health monitoring program216 comprises one or more programs, services, tasks, processes orexecutable instructions to provide logic, rules, functions or operationsfor monitoring any activity of the appliance 200. In some embodiments,the health monitoring program 216 intercepts and inspects any networktraffic passed via the appliance 200. In other embodiments, the healthmonitoring program 216 interfaces by any suitable means and/ormechanisms with one or more of the following: the encryption engine 234,cache manager 232, policy engine 236, multi-protocol compression logic238, packet engine 240, daemon services 218, and shell services 214. Assuch, the health monitoring program 216 may call any applicationprogramming interface (API) to determine a state, status, or health ofany portion of the appliance 200. For example, the health monitoringprogram 216 may ping or send a status inquiry on a periodic basis tocheck if a program, process, service or task is active and currentlyrunning. In another example, the health monitoring program 216 may checkany status, error or history logs provided by any program, process,service or task to determine any condition, status or error with anyportion of the appliance 200.

Daemon services 218 are programs that run continuously or in thebackground and handle periodic service requests received by appliance200. In some embodiments, a daemon service may forward the requests toother programs or processes, such as another daemon service 218 asappropriate. As known to those skilled in the art, a daemon service 218may run unattended to perform continuous or periodic system widefunctions, such as network control, or to perform any desired task. Insome embodiments, one or more daemon services 218 run in the user space202, while in other embodiments, one or more daemon services 218 run inthe kernel space.

Referring now to FIG. 2B, another embodiment of the appliance 200 isdepicted. In brief overview, the appliance 200 provides one or more ofthe following services, functionality or operations: SSL VPNconnectivity 280, switching/load balancing 284, Domain Name Serviceresolution 286, acceleration 288 and an application firewall 290 forcommunications between one or more clients 102 and one or more servers106. Each of the servers 106 may provide one or more network relatedservices 270 a-270 n (referred to as services 270). For example, aserver 106 may provide an http service 270. The appliance 200 comprisesone or more virtual servers or virtual internet protocol servers,referred to as a vServer, VIP server, or just VIP 275 a-275 n (alsoreferred herein as vServer 275). The vServer 275 receives, intercepts orotherwise processes communications between a client 102 and a server 106in accordance with the configuration and operations of the appliance200.

The vServer 275 may comprise software, hardware or any combination ofsoftware and hardware. The vServer 275 may comprise any type and form ofprogram, service, task, process or executable instructions operating inuser mode 202, kernel mode 204 or any combination thereof in theappliance 200. The vServer 275 includes any logic, functions, rules, oroperations to perform any embodiments of the techniques describedherein, such as SSL VPN 280, switching/load balancing 284, Domain NameService resolution 286, acceleration 288 and an application firewall290. In some embodiments, the vServer 275 establishes a connection to aservice 270 of a server 106. The service 275 may comprise any program,application, process, task or set of executable instructions capable ofconnecting to and communicating to the appliance 200, client 102 orvServer 275. For example, the service 275 may comprise a web server,http server, ftp, email or database server. In some embodiments, theservice 270 is a daemon process or network driver for listening,receiving and/or sending communications for an application, such asemail, database or an enterprise application. In some embodiments, theservice 270 may communicate on a specific IP address, or IP address andport.

In some embodiments, the vServer 275 applies one or more policies of thepolicy engine 236 to network communications between the client 102 andserver 106. In one embodiment, the policies are associated with aVServer 275. In another embodiment, the policies are based on a user, ora group of users. In yet another embodiment, a policy is global andapplies to one or more vServers 275 a-275 n, and any user or group ofusers communicating via the appliance 200. In some embodiments, thepolicies of the policy engine have conditions upon which the policy isapplied based on any content of the communication, such as internetprotocol address, port, protocol type, header or fields in a packet, orthe context of the communication, such as user, group of the user,vServer 275, transport layer connection, and/or identification orattributes of the client 102 or server 106.

In other embodiments, the appliance 200 communicates or interfaces withthe policy engine 236 to determine authentication and/or authorizationof a remote user or a remote client 102 to access the computingenvironment 15, application, and/or data file from a server 106. Inanother embodiment, the appliance 200 communicates or interfaces withthe policy engine 236 to determine authentication and/or authorizationof a remote user or a remote client 102 to have the application deliverysystem 190 deliver one or more of the computing environment 15,application, and/or data file. In yet another embodiment, the appliance200 establishes a VPN or SSL VPN connection based on the policy engine's236 authentication and/or authorization of a remote user or a remoteclient 103 In one embodiment, the appliance 102 controls the flow ofnetwork traffic and communication sessions based on policies of thepolicy engine 236. For example, the appliance 200 may control the accessto a computing environment 15, application or data file based on thepolicy engine 236.

In some embodiments, the vServer 275 establishes a transport layerconnection, such as a TCP or UDP connection with a client 102 via theclient agent 120. In one embodiment, the vServer 275 listens for andreceives communications from the client 102. In other embodiments, thevServer 275 establishes a transport layer connection, such as a TCP orUDP connection with a client server 106. In one embodiment, the vServer275 establishes the transport layer connection to an internet protocoladdress and port of a server 270 running on the server 106. In anotherembodiment, the vServer 275 associates a first transport layerconnection to a client 102 with a second transport layer connection tothe server 106. In some embodiments, a vServer 275 establishes a pool oftransport layer connections to a server 106 and multiplexes clientrequests via the pooled transport layer connections.

In some embodiments, the appliance 200 provides a SSL VPN connection 280between a client 102 and a server 106. For example, a client 102 on afirst network 102 requests to establish a connection to a server 106 ona second network 104′. In some embodiments, the second network 104′ isnot routable from the first network 104. In other embodiments, theclient 102 is on a public network 104 and the server 106 is on a privatenetwork 104′, such as a corporate network. In one embodiment, the clientagent 120 intercepts communications of the client 102 on the firstnetwork 104, encrypts the communications, and transmits thecommunications via a first transport layer connection to the appliance200. The appliance 200 associates the first transport layer connectionon the first network 104 to a second transport layer connection to theserver 106 on the second network 104. The appliance 200 receives theintercepted communication from the client agent 102, decrypts thecommunications, and transmits the communication to the server 106 on thesecond network 104 via the second transport layer connection. The secondtransport layer connection may be a pooled transport layer connection.As such, the appliance 200 provides an end-to-end secure transport layerconnection for the client 102 between the two networks 104, 104′.

In one embodiment, the appliance 200 hosts an intranet internet protocolor intranetIP 282 address of the client 102 on the virtual privatenetwork 104. The client 102 has a local network identifier, such as aninternet protocol (IP) address and/or host name on the first network104. When connected to the second network 104′ via the appliance 200,the appliance 200 establishes, assigns or otherwise provides anIntranetIP, which is network identifier, such as IP address and/or hostname, for the client 102 on the second network 104′. The appliance 200listens for and receives on the second or private network 104′ for anycommunications directed towards the client 102 using the client'sestablished IntranetIP 282. In one embodiment, the appliance 200 acts asor on behalf of the client 102 on the second private network 104. Forexample, in another embodiment, a vServer 275 listens for and respondsto communications to the IntranetIP 282 of the client 102. In someembodiments, if a computing device 100 on the second network 104′transmits a request, the appliance 200 processes the request as if itwere the client 102. For example, the appliance 200 may respond to aping to the client's IntranetIP 282. In another example, the appliancemay establish a connection, such as a TCP or UDP connection, withcomputing device 100 on the second network 104 requesting a connectionwith the client's IntranetIP 282.

In some embodiments, the appliance 200 provides one or more of thefollowing acceleration techniques 288 to communications between theclient 102 and server 106: 1) compression; 2) decompression; 3)Transmission Control Protocol pooling; 4) Transmission Control Protocolmultiplexing; 5) Transmission Control Protocol buffering; and 6)caching. In one embodiment, the appliance 200 relieves servers 106 ofmuch of the processing load caused by repeatedly opening and closingtransport layers connections to clients 102 by opening one or moretransport layer connections with each server 106 and maintaining theseconnections to allow repeated data accesses by clients via the Internet.This technique is referred to herein as “connection pooling”.

In some embodiments, in order to seamlessly splice communications from aclient 102 to a server 106 via a pooled transport layer connection, theappliance 200 translates or multiplexes communications by modifyingsequence number and acknowledgment numbers at the transport layerprotocol level. This is referred to as “connection multiplexing”. Insome embodiments, no application layer protocol interaction is required.For example, in the case of an in-bound packet (that is, a packetreceived from a client 102), the source network address of the packet ischanged to that of an output port of appliance 200, and the destinationnetwork address is changed to that of the intended server. In the caseof an outbound packet (that is, one received from a server 106), thesource network address is changed from that of the server 106 to that ofan output port of appliance 200 and the destination address is changedfrom that of appliance 200 to that of the requesting client 102. Thesequence numbers and acknowledgment numbers of the packet are alsotranslated to sequence numbers and acknowledgement expected by theclient 102 on the appliance's 200 transport layer connection to theclient 102. In some embodiments, the packet checksum of the transportlayer protocol is recalculated to account for these translations.

In another embodiment, the appliance 200 provides switching orload-balancing functionality 284 for communications between the client102 and server 106. In some embodiments, the appliance 200 distributestraffic and directs client requests to a server 106 based on layer 4 orapplication-layer request data. In one embodiment, although the networklayer or layer 2 of the network packet identifies a destination server106, the appliance 200 determines the server 106 to distribute thenetwork packet by application information and data carried as payload ofthe transport layer packet. In one embodiment, the health monitoringprograms 216 of the appliance 200 monitor the health of servers todetermine the server 106 for which to distribute a client's request. Insome embodiments, if the appliance 200 detects a server 106 is notavailable or has a load over a predetermined threshold, the appliance200 can direct or distribute client requests to another server 106.

In some embodiments, the appliance 200 acts as a Domain Name Service(DNS) resolver or otherwise provides resolution of a DNS request fromclients 102. In some embodiments, the appliance intercepts' a DNSrequest transmitted by the client 102. In one embodiment, the appliance200 responds to a client's DNS request with an IP address of or hostedby the appliance 200. In this embodiment, the client 102 transmitsnetwork communication for the domain name to the appliance 200. Inanother embodiment, the appliance 200 responds to a client's DNS requestwith an IP address of or hosted by a second appliance 200′. In someembodiments, the appliance 200 responds to a client's DNS request withan IP address of a server 106 determined by the appliance 200.

In yet another embodiment, the appliance 200 provides applicationfirewall functionality 290 for communications between the client 102 andserver 106. In one embodiment, the policy engine 236 provides rules fordetecting and blocking illegitimate requests. In some embodiments, theapplication firewall 290 protects against denial of service (DoS)attacks. In other embodiments, the appliance inspects the content ofintercepted requests to identify and block application-based attacks. Insome embodiments, the rules/policy engine 236 comprises one or moreapplication firewall or security control policies for providingprotections against various classes and types of web or Internet basedvulnerabilities, such as one or more of the following: 1) bufferoverflow, 2) CGI-BIN parameter manipulation, 3) form/hidden fieldmanipulation, 4) forceful browsing, 5) cookie or session poisoning, 6)broken access control list (ACLs) or weak passwords, 7) cross-sitescripting (XSS), 8) command injection, 9) SQL injection, 10) errortriggering sensitive information leak, 11) insecure use of cryptography,12) server misconfiguration, 13) back doors and debug options, 14)website defacement, 15) platform or operating systems vulnerabilities,and 16) zero-day exploits. In an embodiment, the application firewall290 provides HTML form field protection in the form of inspecting oranalyzing the network communication for one or more of the following: 1)required fields are returned, 2) no added field allowed, 3) read-onlyand hidden field enforcement, 4) drop-down list and radio button fieldconformance, and 5) form-field max-length enforcement. In someembodiments, the application firewall 290 ensures cookies are notmodified. In other embodiments, the application firewall 290 protectsagainst forceful browsing by enforcing legal URLs.

In still yet other embodiments, the application firewall 290 protectsany confidential information contained in the network communication. Theapplication firewall 290 may inspect or analyze any networkcommunication in accordance with the rules or polices of the engine 236to identify any confidential information in any field of the networkpacket. In some embodiments, the application firewall 290 identifies inthe network communication one or more occurrences of a credit cardnumber, password, social security number, name, patient code, contactinformation, and age. The encoded portion of the network communicationmay comprise these occurrences or the confidential information. Based onthese occurrences, in one embodiment, the application firewall 290 maytake a policy action on the network communication, such as preventtransmission of the network communication. In another embodiment, theapplication firewall 290 may rewrite, remove or otherwise mask suchidentified occurrence or confidential information.

Still referring to FIG. 2B, the appliance 200 may include a performancemonitoring agent 197 as discussed above in conjunction with FIG. 1D. Inone embodiment, the appliance 200 receives the monitoring agent 197 fromthe monitoring service 1908 or monitoring server 106 as depicted in FIG.1D. In some embodiments, the appliance 200 stores the monitoring agent197 in storage, such as disk, for delivery to any client or server incommunication with the appliance 200. For example, in one embodiment,the appliance 200 transmits the monitoring agent 197 to a client uponreceiving a request to establish a transport layer connection. In otherembodiments, the appliance 200 transmits the monitoring agent 197 uponestablishing the transport layer connection with the client 102. Inanother embodiment, the appliance 200 transmits the monitoring agent 197to the client upon intercepting or detecting a request for a web page.In yet another embodiment, the appliance 200 transmits the monitoringagent 197 to a client or a server in response to a request from themonitoring server 198. In one embodiment, the appliance 200 transmitsthe monitoring agent 197 to a second appliance 200′ or appliance 205.

In other embodiments, the appliance 200 executes the monitoring agent197. In one embodiment, the monitoring agent 197 measures and monitorsthe performance of any application, program, process, service, task orthread executing on the appliance 200. For example, the monitoring agent197 may monitor and measure performance and operation of vServers275A-275N. In another embodiment, the monitoring agent 197 measures andmonitors the performance of any transport layer connections of theappliance 200. In some embodiments, the monitoring agent 197 measuresand monitors the performance of any user sessions traversing theappliance 200. In one embodiment, the monitoring agent 197 measures andmonitors the performance of any virtual private network connectionsand/or sessions traversing the appliance 200, such an SSL VPN session.In still further embodiments, the monitoring agent 197 measures andmonitors the memory, CPU and disk usage and performance of the appliance200. In yet another embodiment, the monitoring agent 197 measures andmonitors the performance of any acceleration technique 288 performed bythe appliance 200, such as SSL offloading, connection pooling andmultiplexing, caching, and compression. In some embodiments, themonitoring agent 197 measures and monitors the performance of any loadbalancing and/or content switching 284 performed by the appliance 200.In other embodiments, the monitoring agent 197 measures and monitors theperformance of application firewall 290 protection and processingperformed by the appliance 200.

C. Client Agent

Referring now to FIG. 3, an embodiment of the client agent 120 isdepicted. The client 102 includes a client agent 120 for establishingand exchanging communications with the appliance 200 and/or server 106via a network 104. In brief overview, the client 102 operates oncomputing device 100 having an operating system with a kernel mode 302and a user mode 303, and a network stack 310 with one or more layers 310a-310 b. The client 102 may have installed and/or execute one or moreapplications. In some embodiments, one or more applications maycommunicate via the network stack 310 to a network 104. One of theapplications, such as a web browser, may also include a first program322. For example, the first program 322 may be used in some embodimentsto install and/or execute the client agent 120, or any portion thereof.The client agent 120 includes an interception mechanism, or interceptor350, for intercepting network communications from the network stack 310from the one or more applications.

The network stack 310 of the client 102 may comprise any type and formof software, or hardware, or any combinations thereof, for providingconnectivity to and communications with a network. In one embodiment,the network stack 310 comprises a software implementation for a networkprotocol suite. The network stack 310 may comprise one or more networklayers, such as any networks layers of the Open Systems Interconnection(OSI) communications model as those skilled in the art recognize andappreciate. As such, the network stack 310 may comprise any type andform of protocols for any of the following layers of the OSI model: 1)physical link layer, 2) data link layer, 3) network layer, 4) transportlayer, 5) session layer, 6) presentation layer, and 7) applicationlayer. In one embodiment, the network stack 310 may comprise a transportcontrol protocol (TCP) over the network layer protocol of the internetprotocol (IP), generally referred to as TCP/IP. In some embodiments, theTCP/IP protocol may be carried over the Ethernet protocol, which maycomprise any of the family of IEEE wide-area-network (WAN) orlocal-area-network (LAN) protocols, such as those protocols covered bythe IEEE 802.3. In some embodiments, the network stack 310 comprises anytype and form of a wireless protocol, such as IEEE 802.11 and/or mobileinternet protocol.

In view of a TCP/IP based network, any TCP/IP based protocol may beused, including Messaging Application Programming Interface (MAPI)(email), File Transfer Protocol (FTP), HyperText Transfer Protocol(HTTP), Common Internet File System (CIFS) protocol (file transfer),Independent Computing Architecture (ICA) protocol, Remote DesktopProtocol (RDP), Wireless Application Protocol (WAP), Mobile IP protocol,and Voice Over IP (VoIP) protocol. In another embodiment, the networkstack 310 comprises any type and form of transport control protocol,such as a modified transport control protocol, for example a TransactionTCP (T/TCP), TCP with selection acknowledgements (TCP-SACK), TCP withlarge windows (TCP-LW), a congestion prediction protocol such as theTCP-Vegas protocol, and a TCP spoofing protocol. In other embodiments,any type and form of user datagram protocol (UDP), such as UDP over IP,may be used by the network stack 310, such as for voice communicationsor real-time data communications.

Furthermore, the network stack 310 may include one or more networkdrivers supporting the one or more layers, such as a TCP driver or anetwork layer driver. The network drivers may be included as part of theoperating system of the computing device 100 or as part of any networkinterface cards or other network access components of the computingdevice 100. In some embodiments, any of the network drivers of thenetwork stack 310 may be customized, modified or adapted to provide acustom or modified portion of the network stack 310 in support of any ofthe techniques described herein. In other embodiments, the accelerationprogram 120 is designed and constructed to operate with or work inconjunction with the network stack 310 installed or otherwise providedby the operating system of the client 102.

The network stack 310 comprises any type and form of interfaces forreceiving, obtaining, providing or otherwise accessing any informationand data related to network communications of the client 102. In oneembodiment, an interface to the network stack 310 comprises anapplication programming interface (API). The interface may also compriseany function call, hooking or filtering mechanism, event or call backmechanism, or any type of interfacing technique. The network stack 310via the interface may receive or provide any type and form of datastructure, such as an object, related to functionality or operation ofthe network stack 310. For example, the data structure may compriseinformation and data related to a network packet or one or more networkpackets. In some embodiments, the data structure comprises a portion ofthe network packet processed at a protocol layer of the network stack310, such as a network packet of the transport layer. In someembodiments, the data structure 325 comprises a kernel-level datastructure, while in other embodiments, the data structure 325 comprisesa user-mode data structure. A kernel-level data structure may comprise adata structure obtained or related to a portion of the network stack 310operating in kernel-mode 302, or a network driver or other softwarerunning in kernel-mode 302, or any data structure obtained or receivedby a service, process, task, thread or other executable instructionsrunning or operating in kernel-mode of the operating system.

Additionally, some portions of the network stack 310 may execute oroperate in kernel-mode 302, for example, the data link or network layer,while other portions execute or operate in user-mode 303, such as anapplication layer of the network stack 310. For example, a first portion310 a of the network stack may provide user-mode access to the networkstack 310 to an application while a second portion 310 a of the networkstack 310 provides access to a network. In some embodiments, a firstportion 310 a of the network stack may comprise one or more upper layersof the network stack 310, such as any of layers 5-7. In otherembodiments, a second portion 310 b of the network stack 310 comprisesone or more lower layers, such as any of layers 1-4. Each of the firstportion 310 a and second portion 310 b of the network stack 310 maycomprise any portion of the network stack 310, at any one or morenetwork layers, in user-mode 203, kernel-mode, 202, or combinationsthereof, or at any portion of a network layer or interface point to anetwork layer or any portion of or interface point to the user-mode 203and kernel-mode 203.

The interceptor 350 may comprise software, hardware, or any combinationof software and hardware. In one embodiment, the interceptor 350intercept a network communication at any point in the network stack 310,and redirects or transmits the network communication to a destinationdesired, managed or controlled by the interceptor 350 or client agent120. For example, the interceptor 350 may intercept a networkcommunication of a network stack 310 of a first network and transmit thenetwork communication to the appliance 200 for transmission on a secondnetwork 104. In some embodiments, the interceptor 350 comprises any typeinterceptor 350 comprises a driver, such as a network driver constructedand designed to interface and work with the network stack 310. In someembodiments, the client agent 120 and/or interceptor 350 operates at oneor more layers of the network stack 310, such as at the transport layer.In one embodiment, the interceptor 350 comprises a filter driver,hooking mechanism, or any form and type of suitable network driverinterface that interfaces to the transport layer of the network stack,such as via the transport driver interface (TDI). In some embodiments,the interceptor 350 interfaces to a first protocol layer, such as thetransport layer and another protocol layer, such as any layer above thetransport protocol layer, for example, an application protocol layer. Inone embodiment, the interceptor 350 may comprise a driver complying withthe Network Driver Interface Specification (NDIS), or a NDIS driver. Inanother embodiment, the interceptor 350 may comprise a min-filter or amini-port driver. In one embodiment, the interceptor 350, or portionthereof, operates in kernel-mode 202. In another embodiment, theinterceptor 350, or portion thereof, operates in user-mode 203. In someembodiments, a portion of the interceptor 350 operates in kernel-mode202 while another portion of the interceptor 350 operates in user-mode203. In other embodiments, the client agent 120 operates in user-mode203 but interfaces via the interceptor 350 to a kernel-mode driver,process, service, task or portion of the operating system, such as toobtain a kernel-level data structure 225. In further embodiments, theinterceptor 350 is a user-mode application or program, such asapplication.

In one embodiment, the interceptor 350 intercepts any transport layerconnection requests. In these embodiments, the interceptor 350 executetransport layer application programming interface (API) calls to set thedestination information, such as destination IP address and/or port to adesired location for the location. In this manner, the interceptor 350intercepts and redirects the transport layer connection to a IP addressand port controlled or managed by the interceptor 350 or client agent120. In one embodiment, the interceptor 350 sets the destinationinformation for the connection to a local IP address and port of theclient 102 on which the client agent 120 is listening. For example, theclient agent 120 may comprise a proxy service listening on a local IPaddress and port for redirected transport layer communications. In someembodiments, the client agent 120 then communicates the redirectedtransport layer communication to the appliance 200.

In some embodiments, the interceptor 350 intercepts a Domain NameService (DNS) request. In one embodiment, the client agent 120 and/orinterceptor 350 resolves the DNS request. In another embodiment, theinterceptor transmits the intercepted DNS request to the appliance 200for DNS resolution. In one embodiment, the appliance 200 resolves theDNS request and communicates the DNS response to the client agent 120.In some embodiments, the appliance 200 resolves the DNS request viaanother appliance 200′ or a DNS server 106.

In yet another embodiment, the client agent 120 may comprise two agents120 and 120′. In one embodiment, a first agent 120 may comprise aninterceptor 350 operating at the network layer of the network stack 310.In some embodiments, the first agent 120 intercepts network layerrequests such as Internet Control Message Protocol (ICMP) requests(e.g., ping and traceroute). In other embodiments, the second agent 120′may operate at the transport layer and intercept transport layercommunications. In some embodiments, the first agent 120 interceptscommunications at one layer of the network stack 210 and interfaces withor communicates the intercepted communication to the second agent 120′.

The client agent 120 and/or interceptor 350 may operate at or interfacewith a protocol layer in a manner transparent to any other protocollayer of the network stack 310. For example, in one embodiment, theinterceptor 350 operates or interfaces with the transport layer of thenetwork stack 310 transparently to any protocol layer below thetransport layer, such as the network layer, and any protocol layer abovethe transport layer, such as the session, presentation or applicationlayer protocols. This allows the other protocol layers of the networkstack 310 to operate as desired and without modification for using theinterceptor 350. As such, the client agent 120 and/or interceptor 350can interface with the transport layer to secure, optimize, accelerate,route or load-balance any communications provided via any protocolcarried by the transport layer, such as any application layer protocolover TCP/IP.

Furthermore, the client agent 120 and/or interceptor may operate at orinterface with the network stack 310 in a manner transparent to anyapplication, a user of the client 102, and any other computing device,such as a server, in communications with the client 102. The clientagent 120 and/or interceptor 350 may be installed and/or executed on theclient 102 in a manner without modification of an application. In someembodiments, the user of the client 102 or a computing device incommunications with the client 102 are not aware of the existence,execution or operation of the client agent 120 and/or interceptor 350.As such, in some embodiments, the client agent 120 and/or interceptor350 is installed, executed, and/or operated transparently to anapplication, user of the client 102, another computing device, such as aserver, or any of the protocol layers above and/or below the protocollayer interfaced to by the interceptor 350.

The client agent 120 includes an acceleration program 302, a streamingclient 306, a collection agent 304, and/or monitoring agent 197. In oneembodiment, the client agent 120 comprises an Independent ComputingArchitecture (ICA) client, or any portion thereof, developed by CitrixSystems, Inc. of Fort Lauderdale, Fla., and is also referred to as anICA client. In some embodiments, the client 120 comprises an applicationstreaming client 306 for streaming an application from a server 106 to aclient 102. In some embodiments, the client agent 120 comprises anacceleration program 302 for accelerating communications between client102 and server 106. In another embodiment, the client agent 120 includesa collection agent 304 for performing end-point detection/scanning andcollecting end-point information for the appliance 200 and/or server106.

In some embodiments, the acceleration program 302 comprises aclient-side acceleration program for performing one or more accelerationtechniques to accelerate, enhance or otherwise improve a client'scommunications with and/or access to a server 106, such as accessing anapplication provided by a server 106. The logic, functions, and/oroperations of the executable instructions of the acceleration program302 may perform one or more of the following acceleration techniques: 1)multi-protocol compression, 2) transport control protocol pooling, 3)transport control protocol multiplexing, 4) transport control protocolbuffering, and 5) caching via a cache manager. Additionally, theacceleration program 302 may perform encryption and/or decryption of anycommunications received and/or transmitted by the client 102. In someembodiments, the acceleration program 302 performs one or more of theacceleration techniques in an integrated manner or fashion.Additionally, the acceleration program 302 can perform compression onany of the protocols, or multiple-protocols, carried as a payload of anetwork packet of the transport layer protocol.

The streaming client 306 comprises an application, program, process,service, task or executable instructions for receiving and executing astreamed application from a server 106. A server 106 may stream one ormore application data files to the streaming client 306 for playing,executing or otherwise causing to be executed the application on theclient 102. In some embodiments, the server 106 transmits a set ofcompressed or packaged application data files to the streaming client306. In some embodiments, the plurality of application files arecompressed and stored on a file server within an archive file such as aCAB, ZIP, SIT, TAR, JAR or other archives In one embodiment, the server106 decompresses, unpackages or unarchives the application files andtransmits the files to the client 102. In another embodiment, the client102 decompresses, unpackages or unarchives the application files. Thestreaming client 306 dynamically installs the application, or portionthereof, and executes the application. In one embodiment, the streamingclient 306 may be an executable program. In some embodiments, thestreaming client 306 may be able to launch another executable program.

The collection agent 304 comprises an application, program, process,service, task or executable instructions for identifying, obtainingand/or collecting information about the client 102. In some embodiments,the appliance 200 transmits the collection agent 304 to the client 102or client agent 120. The collection agent 304 may be configuredaccording to one or more policies of the policy engine 236 of theappliance. In other embodiments, the collection agent 304 transmitscollected information on the client 102 to the appliance 200. In oneembodiment, the policy engine 236 of the appliance 200 uses thecollected information to determine and provide access, authenticationand authorization control of the client's connection to a network 104.

In one embodiment, the collection agent 304 comprises an end-pointdetection and scanning mechanism, which identifies and determines one ormore attributes or characteristics of the client. For example, thecollection agent 304 may identify and determine any one or more of thefollowing client-side attributes: 1) the operating system an/or aversion of an operating system, 2) a service pack of the operatingsystem, 3) a running service, 4) a running process, and 5) a file. Thecollection agent 304 may also identify and determine the presence orversions of any one or more of the following on the client: 1) antivirussoftware, 2) personal firewall software, 3) anti-spam software, and 4)internet security software. The policy engine 236 may have one or morepolicies based on any one or more of the attributes or characteristicsof the client or client-side attributes.

In some embodiments, the client agent 120 includes a monitoring agent197 as discussed in conjunction with FIGS. 1D and 2B. The monitoringagent 197 may be any type and form of script, such as Visual Basic orJava script. In one embodiment, the monitoring agent 129 monitors andmeasures performance of any portion of the client agent 120. Forexample, in some embodiments, the monitoring agent 129 monitors andmeasures performance of the acceleration program 302. In anotherembodiment, the monitoring agent 129 monitors and measures performanceof the streaming client 306. In other embodiments, the monitoring agent129 monitors and measures performance of the collection agent 304. Instill another embodiment, the monitoring agent 129 monitors and measuresperformance of the interceptor 350. In some embodiments, the monitoringagent 129 monitors and measures any resource of the client 102, such asmemory, CPU and disk.

The monitoring agent 197 may monitor and measure performance of anyapplication of the client. In one embodiment, the monitoring agent 129monitors and measures performance of a browser on the client 102. Insome embodiments, the monitoring agent 197 monitors and measuresperformance of any application delivered via the client agent 120. Inother embodiments, the monitoring agent 197 measures and monitors enduser response times for an application, such as web-based or HTTPresponse times. The monitoring agent 197 may monitor and measureperformance of an ICA or RDP client. In another embodiment, themonitoring agent 197 measures and monitors metrics for a user session orapplication session. In some embodiments, monitoring agent 197 measuresand monitors an ICA or RDP session. In one embodiment, the monitoringagent 197 measures and monitors the performance of the appliance 200 inaccelerating delivery of an application and/or data to the client 102.

In some embodiments and still referring to FIG. 3, a first program 322may be used to install and/or execute the client agent 120, or portionthereof, such as the interceptor 350, automatically, silently,transparently, or otherwise. In one embodiment, the first program 322comprises a plugin component, such an ActiveX control or Java control orscript that is loaded into and executed by an application. For example,the first program comprises an ActiveX control loaded and run by a webbrowser application, such as in the memory space or context of theapplication. In another embodiment, the first program 322 comprises aset of executable instructions loaded into and run by the application,such as a browser. In one embodiment, the first program 322 comprises adesigned and constructed program to install the client agent 120. Insome embodiments, the first program 322 obtains, downloads, or receivesthe client agent 120 via the network from another computing device. Inanother embodiment, the first program 322 is an installer program or aplug and play manager for installing programs, such as network drivers,on the operating system of the client 102.

D. Systems and Methods for Configuring and Using Object-Oriented PolicyExpressions

Referring now to FIG. 4A, an example of a portion of an object modelused to facilitate processing of HTTP data is shown. In brief overview,object classes are defined for a number of elements in the HTTPprotocol. Defined classes include a request 405, response 410, hostname415, url 420, query 425, cookie 430, and text 435. Each class is definedto include a number of fields and/or methods, which may include orreturn objects corresponding to other classes or may include or returnother data types, such as integers.

Still referring to FIG. 4A, now in greater detail, an object model maycomprise a set of defined object classes which allows a computing deviceto specify and manipulate data, and/or a set of defined object classeswhich allows a user of a computing device to direct the operations ofthe computing device. An object model may have any properties associatedwith object-oriented design or programming including, withoutlimitation, inheritance, abstraction, encapsulation, and polymorphism.Examples of object models that may be used in conjunction with theobject-oriented expressions described herein include, withoutlimitation, the Java object model, the Component Object Model (COM), andthe HTML Document Object Model (DOM), and any portion or combinations ofportions of those models. In some embodiments, an object model or aportion of an object model may correspond to a protocol. For example, anobject model may be created to represent HTTP communications, with theobject model providing classes and methods for accessing andmanipulating HTTP communications. Or an object model may be created torepresent TCP, IP, UDP, ICA, or SSL communications. Or an object modelmay be created to represent an appliance, with the object modelproviding classes and methods for accessing and manipulating stateinformation relating to an network appliance 200.

An object class may comprise an abstract description of an object andany methods associated with the object. An object, a particular instanceof a class, may represent any type or form of data, process, orprotocol. Example objects may include, without limitation, strings,text, numbers, lists, protocols, data streams, connections, devices,data structures, systems, and network packets.

An object class may have a number of members. A member of an objectclass may comprise any field, method, constructor, property, or variablespecified by the object class. In some embodiments, a member of anobject class may comprise an object of a second object class. Forexample, in the embodiment shown, the object class “http_request” 405contains a method “getUrl” which returns a url object. In otherembodiments, a member of an object class may be a primitive data type ofan underlying architecture, such as an integer, floating point number,byte, array, or boolean variable. For example, the class“cookie”contains a field “count” which is an integer identifying thenumber of name-value pairs in the list. In still other embodiments, amember of an object class may comprise a constant. In still otherembodiments, a member of an object class may comprise a method.

In some cases, a member of an object class may be defined in the objectclass definition. In other cases, a member of an object class may bedefined in a parent class of the object class. In still other cases, amember of an object class may be defined in a parent of the object classand modified in the class definition for the object. For example, boththe “cookie” 430 and “query” 425 classes inherit the methods “getName”and “getValue” from their parent class “list_nv” which is a classrepresenting lists of name-value pairs.

In the embodiment shown, the http_request class 405 contains a number ofmethods which may be used to process an HTTP request. Fields and methodsme be provided to identify and manipulate any portion or portions of anHTTP request including, without limitation, the URL, cookie, body,content-type, date, version, and hostname. In one embodiment, a methodor methods may be provided to determine whether a given data stream is avalidly formatted HTTP request. A similar class and/or methods may alsobe provided for an HTTP response.

The url class 420 shown may comprise any number of fields and methodsfor operating and identifying a url. In one embodiment, the url maycontain methods for parsing one or more of a hostname, port, server,domain, file suffix, path, and query. In one embodiment, the url may bea subclass of a general text object, which may allow the url to betreated as unformatted text. For example, the url class 420 may be asubclass of the text class 435. In one embodiment, the url class maycomprise methods for rewriting all or a portion of the url. In someembodiments, the url class may be applied to any portion of text. Forexample, the url class may comprise a constructor which accepts a stringof text and creates a url object by parsing the string. In these andother embodiments, the url class may comprise a method for indicatingwhether a URL is a properly formatted URL. In some embodiments, a URLclass may comprise a method for identifying one or more URLs in a textstring. For example, a static method “findURL” might be provided whichreturns a list of validly formatted URLs in a given text sequence. Thismethod could be used, for example, to find a number of URLs contained inthe body of an HTTP response. The url class may then provide methods formodifying one or more of the found URLs.

The cookie class 430 may comprise any number of fields and methods foridentifying and processing a cookie. In one embodiment, the cookie maybe an HTTP cookie. In the embodiment shown, the cookie class representsa cookie as a list of name value pairs. The “getValue” method, inresponse to receiving a number n, may return a text object of the nthvalue in the list. The getName method, in response to receiving a numbern, may return a text object of the nth value in the name. In otherembodiments, a cookie may be represented using any other syntax or datatype including, without limitation, a string, or linked list. In someembodiments, the cookie class may provide a method for inserting and/oraltering a cookie. In other embodiments, a HTTP response or requestobject class may provide a method for inserting or modifying a cookiecontained in a request or response.

The “text” class 435 shown may comprise any number of fields and/ormethods for operating on a text sequence. A text sequence may compriseany sequence of bytes capable of being treated as characters. In someembodiments, a text object may comprise a discrete sequence of bytes. Inother embodiments, a text object may comprise one or more bytes of abyte stream. In these embodiments, a text object may be used to operateon portions of the byte stream even if the entire stream has not beenreceived. Methods that may be used in conjunction with text objects mayinclude, without limitation, comparisons, truncations, searches, sorts,and regular expression matching and searching. For example, a method maybe provided to determine whether a given substring is found within atext object. Or for example, a method may be provided to determine aportion of a text object preceding a special character. Or, for example,a method may be provided for identifying a sequence of text following agiven regular expression.

In some embodiments, methods may also be provided for formatting orconfirming formatting of text so that it can be processed by otherclasses and/or methods. For example, a method may be provided thatensures a text object may be treated as XML. This method might checkthat the text object conforms to proper XML formatting and does notcontain any malicious or inadvertent errors. Or, for example, a similarmethod may be provided to determine whether a text sequence can betreated as a URL. This method may, for example, find and replace anycharacters which need to be replaced by escape sequences so that thetext object conforms to proper URL formatting conventions.

An object model may be implemented using any physical data structures orother underlying physical implementations. In some embodiments, a numberof objects may access the same object in physical memory to perform themethods associated with each object. In one embodiment, the object modelshown may be implemented so that a plurality of object instances operateon a underlying data stream, without needing to produce separate copiesof the data stream for each object instance. To give a detailed example,with respect to the object model shown, an appliance may receive an HTTPcommunication from a client and store it in memory. The appliance maythen execute identify a http_request object, and then call functions inthe http_request object class 305 to obtain a url and/or a cookieobject. The appliance may then call addition functions or referencefields in the url and cookie objects. Some or all of these methods mayoperate by parsing some or all of the underlying data stream, and thenreturning references to portions of the stream. For example, a urlobject may store the beginning and ending memory locations of the url inthe underlying data stream. Each method of the url class may then parseand/or modify portions of data within the identified memory locations.In this manner, the appliance may be able to process a data stream usingan object model without having to maintain additional copies of data inthe data stream.

In other implementations, one or more additional copies of some or allof a data stream may be made with respect to some objects. These objectmay perform operations on a copy of a portion of data stream, and, asmay be appropriate, update the data stream with any changes made to thecopy.

The object model shown and others may specify object classes and datastructures that can be applied to any input stream. For example, theobject model shown may be used to treat any input stream as anhttp_request object, and then utilize any of the functionality providedby the http_request object class. Further, although the object modelshown relates to HTTP data, other object models may be used to providefunctionality with respect to TCP, SSL, or ICA streams. In someembodiments, an object model and implementation may be provided suchthat an appliance may select from a number of object models to process agiven data stream. For example, upon receiving a given data stream, anappliance may determine that the data stream is an ICA stream, and applyan appropriate object model for processing the ICA stream. However, ifHTTP data is transmitted within the ICA stream, the appliance may alsoapply an HTTP object model, such as the one shown, for processing theHTTP data. In this way, an appliance may specify any structure orstructures to apply to a received byte stream.

Referring now to FIG. 4B, an example documentation screen for an objectclass representing a URL is shown. In brief overview, the documentationscreen comprises a partial list of a number of methods and a constructorfor the “http_url_t” class, which represents a URL. The documentationscreen indicates a number of methods are implemented in the “http_url_t”class, and a number of methods implemented in the parent class “text_t.”These classes may correspond to the “url” and “text” classes describedwith respect to FIG. 4A.

Referring now to FIG. 4C, a number of example object-orientedexpressions for use in a policy engine are shown. In brief overview, anobject oriented expression 400 contains a number of object classes,which may correspond to protocols, protocol objects, data structures,and data types. An object-oriented expression may specify a member of anidentified object, which may comprise methods, data types, or otherobject classes. A number of example object-oriented expressions 400 a,400 b, 400 c are shown. These object oriented expressions may be used bya network device in performing any function including, withoutlimitation, analyzing traffic flows, identifying system properties, loadbalancing, content switching, and application security.

Still referring to FIG. 4C, now in greater detail, object-orientedexpressions may comprise any expression which allows the specificationof data and functions with respect to an object model. A first exampleobject oriented expression 400 identifies an object class and a memberof the object class. In the syntax of the object-oriented expressionsshown, a member of an object is designated by a period following theobject and then a string naming the member of the object. For example,HTTP.REQ identifies the member method named “REQ” for the HTTP object.In this example, method names may be denoted with all uppercase. Inother embodiments, any other syntax may be used to specifyobject-oriented expressions. Examples of syntaxes that may be usedinclude, without limitation, the syntax or a combination of syntaxes ofActionScript, Java, JavaScript, C#, Visual FoxPro, VB.Net, C++, Python,Perl, PHP, Ruby and/or Objective-C.

In the example object-oriented expression 400 a, the expressionidentifies the protocol HTTP. In one embodiment, HTTP may correspond toan object class, an abstract object class, a static object class, or anyother component of an object model. In some embodiments, HTTP may be aparent class of a number of object classes used to represent and processHTTP communications. In other embodiments, “HTTP” may be a static classor method comprising one or more objects and/or methods relating to therepresentation and processing of HTTP communications. For example, theexpression “HTTP.REQ” may return an object corresponding to an HTTPrequest within a data stream. In one embodiment, this object may be aninstance of an object class such as the “http_request” class discussedin FIG. 4A. In the embodiment shown, the expression 400 a may return aboolean value indicating whether “joe” is contained in a value named“id” in the query portion of a URL of an HTTP request.

The example object-oriented expression 400 b provides an example ofexplicit typecasting, which may be used to specify structure withrespect to arbitrary portions of a data stream. In the example, thestring returned from a HTTP request header item corresponding to theAccept-Language is explicitly typecast into a list. The TYPECAST_TO_LISTmethod accepts as an argument the list delimiter, and returns a listbased on the delimiter. The expression then identifies a CONTAINS methodto determine whether one of the list elements is “en”. This example 400b may be used to configure a device to detect whether an HTTP requestindicates the requestor accepts English as a language. In someembodiments, an object model and expression syntax may allow a datastream to be explicitly typecast into any object class. This may allow auser configuring a device to specify arbitrary structures to be appliedwith respect to a data stream. This may in turn allow a user to leverageknowledge of a protocol or convention to format input streams in amanner convenient for processing.

As another example of an explicit typecasting, the expressionHTTP.RES.HEADER(“Location”).TYPECAST_TO_URL.QUERY may be used totypecase an element of the HTTP header so that it is treated as a URL.By typecasting text elements to a URL, the URL processing methods may bemade available to analyze content in any portion of a network trafficstream.

In some embodiments, two or more object-oriented expressions may be usedin conjunction with an operator, such as AND, OR, NOT, GREATER THAN, orLESS THAN, to produce a value. For example, in expression 400 c twoexpressions which may return boolean values are joined with an ORoperator. The result of the combined expression will be the OR of thevalues returned by the two expressions. In other embodiments, operatorsmay work with respect to any objects or data types including, withoutlimitation, integers, floating point numbers, and strings.

Though the specific examples shown reflect object-oriented statement inthe context of an HTTP object model, object-oriented statements andmodels may be used to access any portions or portion of network trafficpassing through a device. In addition, object-oriented statements andmodels may be used to access system properties of a device, orproperties of a given connection or connected device.

In one embodiment, an object-oriented expression may be used to basenetwork device behavior on any properties of the device. For example,the expression SYS.TIME.WITHIN(time1, time2) might be used to basebehavior based on a time of day, or day of year. Or, for example, theexpression SYS.CONNECTIONS.SSL_OPEN.COUNT might be used to return acount of the total number of SSL connection are currently open with asystem. In both of these examples, the SYS object represents the systemexecuting the policy, and a number of methods and/or fields are providedwithin the SYS object to access information about system status.

In another embodiment, an object-oriented expression may be used to basenetwork device behavior on any properties of a client connected to thedevice. In one embodiment a “CLIENT” object might be provided torepresent the properties of a client sending or receiving a currentlyprocessed data stream. For example, the expression:CLIENT.IP.SRC.IN_SUBNET(10.100.202.0/24), might be used to return atrue/false value based on whether a client corresponding to a datastream is in a given subnet. Or, for example, the expressionCLIENT.AGENT.VERSION_NUM might be used to retrieve the version number ofa client agent executing on the client. Or, for example, the expressionCLIENT.VLAN.VIRTUAL_IP might be used to access the virtual IP address ofa client.

In still another embodiment, an object-oriented expression may be usedto base network device behavior on any property of a server connected tothe device. For example, SERVER.METRICS.HTTP.AVG_RESP_TIME might be usedto access the average response time of a server for generating HTTPrequests. Or, for example, SERVER.ICA.MAX_CONNECTIONS. might be used toidentify a maximum number of ICA connections specified for a givenserver. Or, for example, SERVER.ETHER.HEADER might be used to identifythe ethernet packet headers of a given connection to a server.

In some embodiments, an object-oriented expression may be used to buffera certain amount of a communication before or during processing. Forexample, an appliance serving as a proxy for HTTP communications maywish to base some behavior on an initial part of the response. In thiscase, it may be desirable to only buffer a portion of the response, sothat end-to-end response time does not unduly suffer. In one embodiment,an expression may specify a number of bytes to receive before anexpression is evaluated. For example, the expressionHTTP.REQ.getBody(5000).TYPECAST_TO_NV_LIST(‘=’, ‘&’).getValue(“id”) maybe used to buffer the first 5000 bytes of an HTTP request body, and thentreat those bytes as a name-value pair list. The expression thenspecifies to get the value corresponding to the name “id.”

Referring now to FIG. 5, an example of a policy which may be used inconfiguring a device is shown. In brief overview, a policy 500 comprisesan expression 510 which may be evaluated in the context of a rule 505. Apolicy 500 may also comprise an action 515 which specifies an action tobe taken if the rule is satisfied.

Still referring to FIG. 5, now in greater detail a policy may be used toconfigure a device. In some embodiments, a policy may be used toconfigure any device including, without limitation, a WAN optimizationappliance 200, an SSL/VPN appliance 200, an acceleration appliance 200,a caching appliance 200, a load balancing appliance, and/or a deviceproviding any combination of features of those devices. In otherembodiments, a policy may be used to configure a client agent or serveragent.

In some embodiments, a policy engine executing on a device mayinterpret, evaluate, and/or execute policies with respect to functionsof the device. For example, a policy engine 236 may execute on anappliance 200 and interpret and execute a number of policies directingother actions and modules of the appliance including, withoutlimitation, an SSL/VPN module 280, an Intranet IP module 282, aswitching module 284, a DNS module 286, an acceleration module 288, anapplication firewall module 290, and/or a monitoring agent 197. In someembodiments a single set of policies may be provided for directing aplurality of appliance functions. In other embodiments, a separate setof policies may be used to configure each of a number of appliancefunctions. Policies may be stored in any manner within a device. In someembodiments, a policy may be compiled before it is executed on a device.In other embodiments, a policy may be interpreted at runtime.

A policy 500 may comprise one or more expressions 510. An expression ina policy may be evaluated by a device at runtime with respect to theobjects specified in the expression to produce a value. An expression510 may be any type of expression. In one embodiment, an expression 510may be an object-oriented expression. An expression may be used anywherewithin a policy. In some embodiments an expression may be specified in arule of a policy. In other embodiments, an expression may be specifiedin an action of a policy.

A policy 500 may also comprise a rule 505. The rule may be evaluated atruntime with respect to objects, methods, and operators identified inthe rule to produce a result. Depending on the result, the appliance maythen execute one or more actions specified in the policy. For example,if a rule evaluates to “true” an appliance may execute the actionassociated with the rule. Or if a rule evaluates to “false” andappliance may not execute the action associated with the rule. In someembodiments, a rule may comprise a single expression. In otherembodiments, a rule may comprise a plurality of expressions connected byoperators.

A policy 500 may also comprise an action 515. An action may specify anyaction to be taken. Examples of actions may include, without limitation,blocking or allowing a data stream, forwarding a data stream or objectto a given server or device, storing an object in memory, altering aportion of a data stream, altering one or more system properties,performing an acceleration technique, and performing a compressiontechnique. In the policy 500 shown, upon determining that an HTTPrequest URL contains a user identifier of “JOE”, the policy dictates anaction of forwarding the request to a specified server. In someembodiments, an action may comprise an expression to be evaluated atruntime

Referring now to FIG. 6, an example of an expression input screen 600for a user to input an object-oriented expression is shown. In briefoverview, an expression input screen 600 comprises a number of pull-downmenus 620 which allow a user to specify members of classes to include ina created expression. The screen 610 may also comprise a display where auser may be able to see and/or edit a text version of the expression.The screen may further comprise a display 630 which displays to the userinformation corresponding to one or more objects.

Still referring to FIG. 6, now in greater detail, an expression inputscreen allows input of object oriented expressions by a user in anymanner. In the embodiment shown, pull-down menus 620 may be used toselect objects. In other embodiments, any other input elements may beused to accept an object oriented expression including, withoutlimitation, text fields, menus, buttons, checkboxes, and toolbars. Insome embodiments, input elements of a screen 600 may providefunctionality for a user to create and verify valid expressions. In someembodiments, the pull-down menus 620 may be automatically populated withmembers of the previous specified class. For example, upon a userselecting “URL” in the menu shown, the next pull down menu may bepopulated with the members of the URL object class. In this way a usermay be able to efficiently navigate class hierarchies and object modelsto generate an expression. In other embodiments, syntax highlighting,auto-completion, and/or auto-recommendation may be used to enable a userto easily create and verify expressions. For example, a user may beprovided with a text field 610 to compose an expression, wherein thetext field highlights in red any unrecognized objects or syntax. Or forexample, a user may be provided with a text field 610 which, upon a usertyping an object class, the text field displays a list of members of theobject class.

In some embodiments, an expression input screen 600 may display to theuser information about any objects or expressions. In some embodiments,the screen 600 may display the properties and/or recommended uses of agiven class. In one embodiment, the screen 600 may be integrated with orused alongside one or more class documentation screens such as depictedin FIG. 4B.

Referring now to FIG. 7A, an example of a configuration interface screenwhich may be used to configure a plurality of policies corresponding toone or more network devices is shown. In brief overview, a screendisplays a list of network device functions 710 with folders containingone or more policies, policy groups, or settings related to thefunctions. In the example shown, the screen displays folders for systempolicies, network policies, DNS policies, SSL policies, SSL offloadpolicies, compression policies, integrated caching policies, protectionfeatures, load balancing policies, content switching policies, cacheredirection policies, global load balancing policies, SSL VPN policies,and application security policies. In some embodiments, a number ofpolicies, policy groups, and/or settings corresponding to a function maybe referred to as a profile.

Still referring to FIG. 7A, now in greater detail, a configurationinterface may allow a user to specify policies or settings related toone or more network devices. In some embodiments, a configurationinterface may be used to configure an appliance 200 including, withoutlimitation, a VPN appliance, acceleration appliance, or WAN optimizationdevice. In some embodiments, a single configuration interface may allowa user to configure a plurality of appliances. For example, a user maybe able to specify one or more appliances to apply a given policy,policy group, or setting to. In one embodiment, a user may be able tospecify that a number of appliances share a configuration profile. Forexample, a user may configure a cluster of appliances 200 such that eachappliance has the same policy settings. In other embodiments, aconfiguration interface 700 may be used to configure one or more clientagents 120.

A configuration interface 700 may comprise any means of collecting inputincluding, without limitation, GUIs, and command-line interfaces. Aconfiguration interface may comprise one or more expression inputscreens 600. In one embodiment, a configuration interface may readconfiguration information from a file. In another embodiment, aconfiguration interface may receive configuration information over anetwork. For example, a configuration interface 700 may comprise meansfor a user to download one or more policies, settings, policy groups, orprofiles. These may comprise commonly used policies or settings for anumber of applications.

A configuration interface may obscure any aspects of a policy, policygroup or configuration from a user. For example, a configurationinterface may fill in any portions of a policy or policy groupautomatically or by default such that the user does not need to activelyconfigure those portions. For example, a configuration interface mayprovide a default list of actions, where the user only needs to specifya list of rules under which the actions should be taken. The syntax andimplementation of the actions may be completely or partially hidden fromthe user.

Referring now to FIG. 7B, an example of using a computer to configure anappliance using a configuration interface is shown. In brief overview, aconfiguration interface 700 comprising an expression input screen 500 isdisplayed on a client 102. The client 102 transmits the configurationdata received via the configuration interface to the appliance 200.

Still referring to FIG. 7B, now in greater detail, a configurationinterface 700 may be displayed on a client 102 in any manner. In someembodiments, a configuration interface 700 may comprise an applicationexecuting on the client. In other embodiments, a configuration interface700 may comprise a web page displayed by the appliance. In still otherembodiments, a configuration interface 700 may comprise a web pagedisplayed by a third device.

A configuration interface 700 may comprise any means for a user to inputconfiguration data including, without limitation, text fields, menus,buttons, windows, checkboxes, and drag-and-drop functions. In someembodiments, a configuration interface 700 may comprise an expressioninput screen 500. In other embodiments, a configuration interface mayalso provide screens for a user to input one or more policies. In someembodiments these screen may be integrated with one or more expressioninput screens.

A configuration interface may transmit configuration information to anappliance 200 by any means. The configuration information may betransmitted via any protocol or protocols. In one embodiment,user-inputted configuration information may be saved to a file on theclient 102, and then the file may be transmitted to the appliance. Inother embodiments, a user may input information into a web page or a webapplication which may then transfer the configuration information to theappliance. In some embodiments, the configuration information may becompiled, formatted, or otherwise processed before it is transmitted tothe appliance 200. In still other embodiments, the configurationinformation may be compiled, formatted, or otherwise processed after ithas been received by the appliance.

Referring now to FIG. 8A, an embodiment of a method of configuring anobject-oriented policy of a network device with an object-orientedexpression to specify structure in a payload of a packet stream receivedby a network device is depicted. In brief overview, a configurationinterface 700 is provided by a device in order to configure a policy 600for a network device 200 (step 801). The device receives, via theconfiguration interface 700, an expression 610 for the policy 600 (step803). The device receives, via the configuration interface 700 userinformation identifying an action to be taken based on an evaluation ofthe expression (step 805).

Still referring to FIG. 8A, now in further detail, a configurationinterface may be provided for configuring a policy 600 for a networkdevice 200 in any manner (step 801). In some embodiments theconfiguration interface 700 may comprise a command line interface. Inother embodiments, the configuration interface 700 may comprise agraphical user interface. The configuration interface 700 may compriseone or more of a drag-and-drop interface, a list-selection interface, ora syntax-highlighting interface. In some embodiments, the configurationinterface 700 resides on a client device 102. In other embodiments, theconfiguration interface 700 executes on the network device 200. In someembodiments, a device providing the configuration interface 700 isconnected to an appliance 200 by a network 104. In some embodiments, theconfiguration interface 700 is a webpage. In some other embodiments, theconfiguration interface 700 is a webpage that resides on the networkdevice 200. In other embodiments, the configuration interface 700 is awebpage that resides on a separate server 106.

A device receives, via the configuration interface 700, an expression610 for the policy 600 specifying an object class to apply to a portionof the payload of a packet stream and a member of the object class (step803). In some embodiments, the expression may be received via anexpression input screen 500. In one embodiment, the expression 610identifies a portion of text within a packet stream. In certainembodiments, the expression 610 specifies a protocol, and may alsospecify one or more methods and fields related to the protocol. Forexample, the expression may specify a protocol of HTTP, HTML, FTP, SMTP,ICA, and/or SSL. The specified protocol may then be applied to parse adata stream according to the protocol.

The received expression may specify any object class. For example, thereceived expression may specify any of the object classes described inthe object model of FIG. 4A. An object class may be specified in anymanner. In one embodiment, specifying an object class may comprisespecifying an instance of the object class. For example, the expression“HTTP.REQ” may specify an instance of the “http_request” object fromFIG. 4A. In some embodiments, the received expression may comprise anobject-oriented expression.

The received expression may also specify any member of an identifiedobject class. The member may comprise any object, data type, or method.In some embodiments, the member comprises a field. In other embodiments,the member may comprise a field corresponding to a second object class.In some embodiments, the member of the object class comprises a method.In some embodiments, the member of the object class is inherited from aparent class of the object class. The member of the object class maycorrespond to an HTTP request or response. In other cases, a member ofthe class may be a uniform resource locator (“URL”) or a cookie.

In other embodiments, the expression 610 comprises an explicittypecasting. The explicit typecasting may be used to specify an objectclass to use with respect to a field or returned object. For example, afield containing a number may be explicitly typecast to an alphanumericstring in order to execute a string comparison. Or for example, a streamof bytes may be typecast to a list with a given delimiter. Or forexample, a data stream may be typecast as corresponding a particularprotocol or protocol object.

A device may receive, via the configuration interface 700, informationthat identifies an action 615 for the policy 600, the action 615 to betaken based on an evaluation of the expression 610 (step 805). In someembodiments, the action 615 may comprise an object-oriented expression.In certain embodiments, the method performs the action 615 in order toprovide load-balancing, content switching, application security,application delivery, network acceleration, or application acceleration.For example, in order to accelerate network activity, the method mayevaluate an expression 610 to determine the location of the user and,based on the user's location, route the user's traffic to thegeographically closest server or servers 106. In some embodiments, apolicy may perform security, acceleration, load-balancing or contentswitching functions by rewriting a URL in either the HTTP request orresponse. For example, an action 615 may specify to modify the HTTPrequest so that the URL refers to a specific server or server farm 106.In some cases, the action 615 received from the configuration interface700 may be an expression for “no action” or for a default action.

Referring now to FIG. 8B, an embodiment of a method of applying, by adevice, object-oriented expressions 610 in a policy 600 to specify astructure in a payload of a packet stream received by an appliance 200is depicted. In brief overview, an appliance 200 identifies a policy 600comprising an object-oriented expression 610 to evaluate with respect toa payload of a received packet stream (step 821). The appliance 200assigns values to a data structure specified by the object-orientedexpression 610 based on a portion of the payload (step 823). Theappliance 200 performs an evaluation of the expression 610 based on theassigned values (step 825) and takes, in response to the evaluation, anaction 615 specified by the policy 600 (step 827).

Still referring to FIG. 8B, now in further detail, an appliance mayidentify a policy to apply to a data stream any manner (step 821). Insome embodiments, an appliance may read a policy from one or moreconfiguration files. In other embodiments, a policy engine 236 in anappliance may store a number of policies in memory. In still otherembodiments, an appliance may identify a policy in response to a type orprotocol of the data stream. For example, an appliance may have a set ofpolicies applied to all incoming TCP streams. Or for example, anappliance may identify one or more policies that are applied to SSLstreams. In one embodiment, an appliance may identify a policy based ona sender or a recipient of a data stream. For example, a VPN appliancemay have a set of policies which are applied to incoming connectionrequests from clients. Or an acceleration device may identify one ormore polices to apply to a HTTP stream from a server 106. In someembodiments, the policy may comprise a policy received via aconfiguration interface 700.

The packet stream may be received in any manner, and from any source. Insome embodiments, the packet stream may be transparently intercepted bythe appliance. In other embodiments, the appliance may receive thepacket stream in the process of proxying one or more transport layerconnections. The packet stream may comprise any type of packetsincluding, without limitation, IP packets, TCP packets, UDP packets, andICMP packets. The packet stream may comprise any other protocol orprotocols.

The identified policy may comprise an object-oriented expression toevaluate with respect to the payload of a packet stream. Theobject-oriented expression may comprise any type of object-orientedexpression, and may specify one or more object classes, fields, andmethods. In some embodiments, the object-oriented expression maycomprise part of a rule. In some embodiments, the expression may specifyone or more objects corresponding to a client, server, HTTP protocol, orthe appliance.

The object-oriented expression may be evaluated with respect to anypayload of a packet stream. In one embodiment, the expression may beevaluated with respect to the payload of a TCP or UDP stream. In anotherembodiment, the expression may be evaluated with respect to an SSLstream. In still another embodiment, the expression may be evaluatedwith respect to the payload of an ICA stream. The packet stream may bereceived from any source including, without limitation, a client,server, client agent, server agent, or a second appliance.

The appliance assigns values to a data structure as specified by theobject-oriented expression 610 (step 823). A data structure may comprisethe physical representation of an object instance. In some embodiments,the appliance may parse some or all of the received payload to assignthe values. In other embodiments, the appliance may perform any methodsspecified by the expression or included in an object model to assignvalues. For example, with respect to the expression:

-   -   “HTTP.REQ.HEADER(“Accept-Language”).TYPECAST_TO_LIST(“,”)”        the appliance may assign values to an object corresponding each        of the request, header, and comma-delimited list specified. In        some embodiments, the assigning of values may comprise        determining a portion or portions of the data stream        corresponding to an object. In some embodiments, the step 823        includes applying, by the appliance 200, a class specified by        the object-oriented expression 610 to a byte stream of the        payload. For example, if an expression specifies a URL class,        the appliance may assign a value to an underlying URL data        structure by determining the starting and ending points of a URL        within the received payload. These starting and ending points        may then be stored in a URL data structure and used to perform        any of the methods in the URL class. In some embodiments, the        appliance may assign values to a plurality of data structures        specified by the object-oriented expression. In one embodiment,        a policy engine 236 may perform any functions related to the        evaluation of a policy.

The appliance may perform an evaluation of the expression 610 based onthe assigned values in any manner (step 825). In some embodiments, theappliance may use one or more methods of an object class specified bythe expression to perform the evaluation. In some embodiments, theevaluation may produce a boolean value. In other embodiments, theevaluation may produce an integer, string, or other object. Theappliance may use the assigned values in any manner. In the URL exampleabove, the appliance, after determining a starting and ending point forthe URL, may then use those values to perform any operations withrespect to the URL. In some embodiments, the appliance may then performthe getSuffix( ) method referenced in FIG. 4A, which identifies a filetype suffix of the requested URL. This method may also comprisedetermining a starting and ending point of the suffix in relation to thestarting and ending point of the URL. The appliance may then use thestarting and ending points of the suffix to perform any evaluations ofthe file suffix, such as comparing it to the string “.jsp” to determineif the requested URL corresponds to a Java Server Page.

In some embodiments, the appliance may evaluate a rule comprising theexpression. In other embodiments, the appliance may evaluate a rulecomprising a plurality of expressions.

The appliance may then, in response to the evaluation, take an action615 specified by the policy 600 (step 827). In one embodiment, theappliance takes an action if the result of the evaluation is a valuecorresponding to true. In another embodiment, the appliance may take anaction if the result of the evaluation is non-zero. The action taken maybe any action including, without limitation, any action relating toload-balancing, content switching, application security, applicationdelivery, network acceleration, or application acceleration. In someembodiments, the action 615 may comprise a “no action.”

In some embodiments, the appliance may perform the action immediatelyfollowing the evaluation. In other embodiments, the appliance mayperform the action subsequent to evaluating at least one other policy.In still other embodiments, the appliance may perform the action afterwaiting a predetermined amount of time or waiting until a resourcebecomes available. In one embodiment, the appliance may perform theaction after receiving additional portions of the packet stream.

In some embodiments, the appliance may then forward the received packetstream to one or more appliances servers, clients, or client agents. Theappliance may perform any other network appliance functions with respectto the packet stream including, without limitation, acceleration,compression, and load balancing.

Now referring to FIG. 8C, a method, in an appliance 200, for applyingobject-oriented expressions 610 in a policy 600 to specify structure ina payload of a packet stream received by the appliance 200 is shown. Inbrief overview, the appliance identifies a policy 600 including anobject-oriented expression 610 to evaluate with respect to a payload ofa received packet stream (step 841). The appliance assigns values to adata structure specified by the object-oriented expression 610 based ona portion of the payload (step 843). The appliance also performs anevaluation of the expression 610 based on the assigned values (step845). In response to the evaluation, the appliance alters a portion ofthe received packet stream (step 847) and transmits the altered packetstream (step 849).

Still referring to FIG. 8C, now in greater detail, the appliance mayidentify a policy 600 that specifies an object-oriented expression 610to evaluate with respect to a payload of a received packet stream (step821). This step may be performed in any manner described herein.

The appliance may assign values to a data structure specified by theobject-oriented expression 610 based on a portion of the payload in anymanner (step 823). This step may be performed in any manner describedherein.

The appliance performs an evaluation of the expression based on theassigned values (step 845). This step may be performed in any mannerdescribed herein.

In response to the evaluation, the appliance may alter a portion of thereceived packet stream (step 847). In some embodiments, altering aportion of the received packet stream may comprise taking an action inresponse to the evaluation (step 827). In some embodiments, the portionof the packet stream that is altered is specified by a data structureidentified by the object-oriented expression. In other embodiments, theportion of the packet stream that is altered is specified by a secondobject-oriented expression. In some embodiments, the portion of thepacket stream to be altered may be specified by an object-orientedexpression in an action of the policy. In some embodiments, theappliance may rewrite a URL in the body of an HTTP response or request.In other embodiments, the appliance may rewrite a form field value inthe packet stream. The form field that is altered may be a field in anHTTP request, an HTTP response or any other field in an object that ispart of the packet stream. In still another embodiment, the appliancemay alter one or more name-value pairs contained in the packet stream.In some embodiments, the appliance may rewrite a portion of the receivedpacket stream to obscure or remove confidential data including, withoutlimitation, personal identification numbers, checking account routingnumbers, personal contact information, social security numbers,passwords and other confidential information.

To give a detailed example, upon receiving an HTTP stream from a clientdestined to a server, an appliance providing application securityfunctions for the server may determine to apply a policy:

-   -   if (HTTP.Request.getCookie( ).getValue(“username”).length>20)        then HTTP.Request.getCookie( ).setValue(“username”, “void”)        In this example the appliance may parse some or all of the HTTP        stream to identify the portion of the stream containing the        request, and then the cookie within the request. The appliance        may do this in any manner, including maintaining one or more        internal data structures with references pointers pointing to        the areas of the stream corresponding to the request and cookie.        The appliance may then identify the value of a “username”        name-value pair within the cookie and determine the whether the        length of the value is greater than 20 characters. A length of        over 20 characters may indicate an application error or a        malicious attack, such as an attempted buffer overflow attack.        Upon determining the length is greater than 20 characters, the        appliance may then alter the value to “void” or any other signal        which may notify the server receiving the stream that an        inappropriate value was sent by the client. The appliance may        use and/or modify any internal data structures in order to alter        the stream. The appliance may then forward the altered stream to        the server. In other embodiments, the appliance may simply block        the stream from reaching the server upon detecting the potential        overflow. In these embodiments, the appliance may return an        error message to the client.

In another embodiment, the appliance may replace an entire HTTP responsewith a new response. For example, if the appliance determines that aresponse contains confidential data in a form, the appliance may replacethe response with a response indicating an error or with a responsecomprising neutral content. In yet another embodiment, an appliance mayreplace or rewrite an entire HTTP request or response header.

The appliance may then transmit the altered packet stream in any manner(step 849). In some embodiments, the appliance may forward the alteredpacket stream to a server or client designated as the recipient of thestream. In other embodiments, the appliance may redirect the stream toan appliance, server or client other than the intended recipient of thestream. The appliance may transmit the altered packet stream using anyprotocol or protocols including, without limitation, TCP, IP, UDP, SSL,and ICA.

E. Systems and Methods for Handling Undefined Policy Expressions

Referring now to FIG. 9, an embodiment of a method, in an appliance 200,for applying a policy 600 specifying an action 615 to be taken in theevent an element of the policy 600 is undefined is shown. In briefoverview, an appliance identifies a policy 600 to evaluate with respectto a payload of a received packet stream, where the policy 600 specifies(i) an expression 610, (ii) a first action 615 to take based on theexpression 610 and (iii) a second action 610 to take if an element isundefined (step 901). The appliance determines that an element of thepolicy 600 is undefined with respect to the payload (step 903). Inresponse to its determination that an element is undefined, theappliance takes the second action (step 905). Broadly speaking, themethod allows a policy to specify an action to be taken if an error orexception is encountered when the appliance attempts to evaluate thepolicy. In this manner, the second action may be a fallback orerror-handling method.

Still referring to FIG. 9, now in greater detail, an applianceidentifies a policy 600 to evaluate with respect to a payload of areceived packet stream, where the policy 600 specifies an expression610, a first action 615 to take based on the expression 610 and a secondaction 610 to take if an element of the policy is undefined (step 901).The appliance may identify the policy in any manner. In one embodiment,the expression may be an object-oriented expression. In anotherembodiment, the expression 610 may identify an object class to apply toa portion of the payload of a packet stream and a member of the objectclass. In another embodiment, the expression 610 specifies a protocol,and may also specify one or more related methods and fields. Theexpression may identify any type of object and/or object class. In someembodiments, the expression may comprise one or more methods of anobject class.

The packet stream may be received in any manner and from any source. Insome embodiments, the packet stream may be transparently intercepted bythe appliance. In other embodiments, the appliance may receive thepacket stream in the process of proxying one or more transport layerconnections. The packet stream may comprise any type of packetsincluding, without limitation, IP packets, TCP packets, UDP packets, andICMP packets. The packet stream may comprise any other protocol orprotocols.

The first action specified by the policy may comprise any action. Insome embodiments, the first action may comprise an action to beperformed if the expression or a rule containing the expressionevaluates to true. In some embodiments, the action 615 may relate toload-balancing, content switching, application security, applicationdelivery, network acceleration, or application acceleration. In otherembodiments, either action 615 may comprise to a “no action” or adefault action.

The second action specifies an action to be taken if an element of thepolicy is undefined. An element of the policy may comprise any portionof the policy including, without limitation, one or more expressions,rules, or operators. An element may be undefined in any circumstancewhere an appliance cannot successfully assign a value to the element. Inone embodiment, an element may be undefined if the element results in acomparison of incompatible types such as, for example, determiningwhether an integer is greater than a list, or a boolean value is equalto a string. In other embodiments, an element may be undefined if theelement results in one or more null values. For example, if anexpression attempts to access a “username” value within a URL object andthe expression is applied to a data stream with a URL with no usernamevalue specified, an operation with respect to the username may beundefined. In other embodiments, an element may be undefined as a resultof one or more improper typecasts.

In some embodiments, the second action may have been specified by a uservia a configuration interface. For example, upon entering or viewing apolicy in the configuration interface, a user may be prompted to enteran action to be taken if the policy is undefined at runtime. In otherembodiments, the second action may comprise a preconfigured defaultsecond action. For example, a group of policies may have a defaultaction to take in the event of an undefined element. For example, agroup of policies enabling URL rewriting may have a default secondaction of not rewriting any URLs. Or a group of policies for performingload balancing may have a default second action of forwarding the packetstream to a designated backup server.

The appliance 200 may determine if an element of the policy 600 isundefined with respect to the payload in any manner (step 903). In someembodiments, the appliance may determine that the policy is undefined inthe process of evaluating the policy. In other embodiments, theappliance may determine that the policy is undefined in the process ofprecompiling, compiling or interpreting the policy. In some embodiments,the appliance may determine the policy is undefined by detecting one ormore exceptions generated during the evaluation of the policy. Forexample, the appliance may detect a null pointer, overflow, orarithmetic processing exception during the evaluation of the policy.

In response to the determination that an element is undefined, theappliance may take the second action (step 905). The second action maycomprise any action described herein. In some embodiments, the secondaction may comprise terminating the receipt and or transmission of thepacket stream. In other embodiments, the second action may comprise noaction.

F. Systems and Methods for Configuring and Using Policy Groups

Referring now to FIG. 10A, an example of a policy bank is shown. Inbrief overview, a policy bank 1000 a comprises a group of one or morepolicies with a specified order for evaluation. In the example shown,the order is specified by line numbers for each of the policies. Eachpolicy may also have a flow instruction 1010 a, 1010 b, 1010 c, 1010 d(generally 1010) indicating a policy to be evaluated after evaluation ofthe current policy.

Still referring to FIG. 10A, now in greater detail, a policy bank 1000may comprise any number of policies including, without limitation, 1, 2,3, 4, 5, 6, 10, 20, 50, and 100 policies. The policies of a policy bankmay comprise any policies described herein. In some embodiments, apolicy bank may comprise a group of policies performing a commonfunction. For example, a policy bank may comprise a group of policiesproviding load balancing functions. Or for example, a policy bank maycomprise a group of all the policies for providing caching.

A policy bank may be configured in any manner. In some embodiments, aconfiguration interface 700 may be provided which allows a user tocreate and group one or more polices. In some embodiments, aconfiguration interface may be provided which allows a user to name agiven policy bank. In other embodiments, a configuration interface maybe provided which allows a user to specify one or more attributes of apolicy bank. For example, a policy bank may have a default action toperform in the event of an exception or undefined policy. Or, forexample, a policy bank may have a set of circumstances in which thepolicy bank is applied. For example, a user may specify that a policybank is to be used with respect to all incoming HTTP traffic. Or, forexample, a user may specify a policy bank to be used upon receiving anyconnection requests from new devices. In other embodiments, a policybank may comprise a set of attributes which are used to enforce certaincharacteristics in the policies of the policy bank. For example, apolicy bank may require that no policies in the policy bank access acertain object. The attributes of a policy bank may be enforced atconfiguration time or at runtime.

A policy bank may be stored in any manner. In some embodiments, a policybank may be stored on a file in an appliance. In other embodiments, apolicy bank may be stored in a policy engine 236 of an appliance.

A policy bank may comprise any means of ordering policies forevaluation. In one embodiment, a policy bank may comprise an orderedlist of policies. In other embodiments, a policy bank may comprise a setof policies with one or more flow instructions 1010 indicating anevaluation order. In still other embodiments, a policy bank may comprisea numbered list of policies to be executed in order of increasingnumbers.

Each expression in a policy bank may specify a flow instruction 1010. Aflow instruction 1010 may comprise any information or expressionindicating a policy to be executed in the event the policy containingthe flow instruction evaluates to true. In one embodiment, a flowinstruction may comprise a “NEXT” statement 1010 a, which indicates thatthe next policy in the bank should be evaluated. In another embodiment,a flow instruction may comprise a “GOTO” statement 1010 b whichidentifies another policy in the policy bank to be evaluated next. Insome embodiments, a GOTO statement may identify a policy by a linenumber. In other embodiments, a GOTO statement may identify a policy bya policy name or other identifier. In still another embodiment, a flowinstruction may comprise an “END” statement, which indicates that nomore policies of the policy bank should be evaluated.

In some embodiments, a flow instruction 1010 d may comprise anexpression or expression to be evaluated to determine the policy to beexecuted next. A flow instruction may comprise any expression including,without limitation, any object-oriented expression. For example, theflow instruction 1010 d specifies that an integer following a “servnum”portion of a query should be added to 17 to determine the line of thepolicy to be executed next. In the example policy bank, the flowinstruction 1010 d may be used to distribute HTTP requests among anumber of servers based on a parameter in the requests.

In some embodiments, a configuration interface 700 may be provided withmeans for a user to order policies within a policy bank. Theconfiguration interface may allow a user to specify line numbers,priorities, list ordering, or any other means of specifying evaluationorder. In some embodiments, a configuration interface 700 may allow auser to specify one or more flow instructions with respect to a policyor a policy bank. In other embodiments, the configuration interface mayalso provide any input means for entering one or more flow instructionscorresponding to policies in the policy bank.

Referring now to FIG. 10B, an embodiment of a method of flow controlamong policies 600 used in a network device 200 processing a packetstream is shown. In brief overview, the method includes identifying, byan appliance 200, a plurality of policies 600 to apply to a receivedpacket stream, where at least one of the policies 600 includes a policyidentifier (step 1001). The appliance processes a first policy 600 of aplurality of policies 600, the first policy 600 identifying (i) a rule605 that includes a first expression 610 (ii) a first action 615 to betaken based on an evaluation of the rule 605, and (iii) a second policy600 from among multiple policies (step 1003). Based on an evaluation ofthe expression 610, the appliance determines that the rule 605 evaluatesto true (step 1005). In response to the determination, the appliance 200processes the identified second policy 600 (step 1007).

Still referring to FIG. 10B, now in further detail, the applianceidentifies a plurality of policies 600 to apply to a received packetstream where at least one of the plurality policies specifies a policyidentifier (step 1001). The appliance may identify the plurality ofpolicies in any manner. In some embodiments, the appliance may identifythat the plurality of policies corresponds to policies for a given datastream, data stream source, or data stream recipient. In one embodiment,the plurality of policies may comprise a policy bank.

The packet stream may be received in any manner and from any source. Insome embodiments, the packet stream may be transparently intercepted bythe appliance. In other embodiments, the appliance may receive thepacket stream in the process of proxying one or more transport layerconnections. The packet stream may comprise any type of packetsincluding, without limitation, IP packets, TCP packets, UDP packets, andICMP packets. The packet stream may comprise any other protocol orprotocols.

The at least one policy identifier may comprise any means of identifyinga policy, including, without limitation, a line number, policy name, orpriority number. In some embodiments, each policy 600 of the multiplepolicies 600 specifies a ranking indicating a default order in which thepolicies 600 should be processed.

The appliance 200 processes a first policy 600 of the plurality ofpolicies 600 in which the first policy 600 identifies a rule 605 thatspecifies a first expression 610, a first action 615 to be taken basedon the evaluation of the rule 605, and an expression 610 identifying asecond policy 600 of the plurality of policies 600 (step 1003). Thefirst policy may be processed in accordance with any method forevaluating and processing a policy. In some embodiments, the firstpolicy may comprise an object-oriented expression. In other embodiments,the first policy may comprise a rule comprising an object-orientedexpression.

The first policy may contain any expression identifying a second policy.In some embodiments, the first policy may comprise a name of a secondpolicy. In other embodiments, the first policy 600 includes an integerthat specifies the ranking of a second policy 600 to be processed nextif the first action 615 applies.

In some embodiments, the first policy may comprise a flow instruction1010. The first policy may comprise any flow instruction, including“next,” “goto,” or “end.” The first policy may comprise any otherelements including, without limitation, an action to be performed if anelement of the first policy is undefined. In one embodiment, each policyof the plurality of policies may comprise a flow instruction.

Based on the evaluation of the expression 610 by the appliance 200, theappliance determines the rule 605 evaluates to true (step 1005). In someembodiments, this step includes evaluating an object-oriented expression610.

In response to the determination that the rule evaluates to true, theappliance 200 may process the identified second policy 600 (step 1007).In one embodiment, step 1007 may comprise executing a flow instructionspecified by the first policy. In some embodiments, the appliance 200may evaluate an expression 610 to determine a ranking of a second policy600 from among the multiple policies 600 to be processed next. In someother embodiments, the appliance 200 may evaluate an object-orientedexpression 610 to determine a ranking of a second policy 600 among themultiple policies 600 to be processed next. For example, the appliancemay evaluate an expression to determine a line number to be used inconjunction with a GOTO flow instruction. After determining the linenumber, the appliance may then process the policy at the given linenumber.

In some embodiments, the appliance may also take the action specified bythe first policy upon determining the rule is true. In otherembodiments, upon determining the rule is true, the appliance may storethe action specified by the first policy in a list. This list may beused to store a number of actions to be taken. In one embodiment, as anappliance processes a number of policies in a policy bank, the appliancemay store a list of actions for each policy that contained a rule thatevaluated to true. After processing the number of policies, theappliance may then take all of the actions stored in the list. Inanother embodiment, as an appliance processes a plurality of policybanks, the appliance may store a list of actions for each policy thatcontained a rule that evaluated to true. After processing the number ofpolicy banks, the appliance may then take all of the actions stored inthe list.

Referring now to FIG. 11A, a block diagram illustrating flow controlamong a plurality of policy groups is shown. In brief overview, a policybank 1000 b comprises a number of policies. One of the policiescomprises an invocation action 1110 which invokes a second policy bank1000 c. The invocation action 1110 indicates a policy bank 1000 c to beprocessed if the rule of the policy containing the action evaluates totrue. After processing the invoked policy bank, an appliance may thenresume processing the first policy bank 1000 b. This processing will befurther described with respect to FIG. 11B.

Still referring to FIG. 11A, a configuration interface 700 may beprovided which allows a user to specify an order of execution amongpolicy groups by including one or more invocation actions 1110. Aninvocation action may identify a policy group in any manner including,without limitation, by name, by memory location, or by any otheridentifier. In some embodiments, the policy groups may comprise policybanks. In still other embodiments, an invocation action 1110 may specifya specific policy within a second policy bank.

In some embodiments, an invocation action 1110 may include one or moredirectives indicating how the second policy group is to be processed. Inone embodiment, an invocation action 1110 contained in a first policybank may specify whether or not processing of the first policy bankshould be resumed after processing the invoked policy bank. In anotherembodiment, an invocation action 1110 may specify whether or notprocessing of the first policy bank should be resumed if a hard stop orexception is encountered in the invoked policy bank. For example, aninvocation action may specify that if an “END” flow instruction isencountered in the second policy bank, that processing should resumewith the first policy bank. Or an invocation action may specify that ifan exception or “END” flow instruction is encountered in the secondpolicy bank, that no more policies of the first policy bank should beprocessed.

In this manner, a user may configure a number of policy banks to ensurethat certain policies are processed, even where the results of one ormore policy banks are uncertain. For example, a policy bank providingpolicies for denying access to restricted URLs may invoke a policy bankfor providing SQL security upon detecting that a URL indicates that arequest contains SQL queries. The invocation may specify that regardlessof the outcome of the SQL security policy bank processing, processingshould resume at the URL module after the processing of the SQL policybank. In this manner, the user may be assured that all of the restrictedURL enforcement policy bank are executed, which may ensure that allrestricted URLs are blocked.

A user may also use policy bank invocation actions 1110 to ensure thatpolicies are not evaluated in the event a given policy bank encountersan exception or hard stop. For example, a policy bank providing contentswitching policies may, after determining an application correspondingto a request, may invoke a policy bank containing application securitypolicies for the application. The invocation may indicate that if theapplication security policy bank encounters an “END” instruction, nomore policies are to be evaluated in the content switching policy bank.This may be used in cases where an “END” instruction in the applicationsecurity policy bank indicates that a security requirement has not beenmet, and thus no more processing of the request should be done.

In some embodiments, an appliance may be configured with one or moredefault execution orders for policy groups. For example, an appliancemight have one or more global policy groups which are always appliedfirst, followed by one or more appliance or vServer specific policygroups which are processed following the global policy groups. In someembodiments, policy banks may have a default ordering responsive to thefunctions the policy banks perform. For example, a policy bank of SSLpolicies may be applied first to incoming traffic, and then a set ofsecurity policies may be to the decrypted traffic, followed by a bank ofcontent switching policies.

Referring now to FIG. 11B, an embodiment of a method of flow controlamong policy groups used in a network device 200 processing a packetstream is shown. In brief overview, an appliance identifies a firstpolicy group to apply to a received packet stream (step 1101). Theappliance processes a first policy of the first policy group, where thefirst policy identifies (i) a rule 605 specifying a first expression610, and (ii) information identifying a second policy group (step 1103).The appliance evaluates the rule 605 (step 1105). In response to theevaluation of the rule 605, the appliance processes the identifiedsecond policy group (step 1107). After processing the second policygroup, the appliance processes a second policy 600 of the first policygroup (step 1109).

Still referring to FIG. 11B, now in greater detail, an appliance mayidentify a first policy group to apply to a received packet stream inany manner (step 1101). The packet stream may be received from anysource and may comprise any protocol or protocols.

In some embodiments, the first policy may comprise an object-orientedexpression. In other embodiments, the first policy may comprise a ruleincluding at least one expression and/or object-oriented expression. Insome embodiments, the first policy 600 specifies an action 615 to betaken based on an evaluation of the rule 605.

The information identifying a second policy group may comprise any formof identifying information. In one embodiment, the second policy groupmay comprise a policy bank, and the identifying information may comprisea name of the policy bank. In some embodiments, the informationidentifying the second policy bank may comprise an invocation action1110.

The appliance may process the first policy 600 in any manner (step1103). The appliance may evaluate one or more object orientedexpressions in processing the policy.

The appliance 200 may evaluate the rule 605 in any manner (step 1105).In some embodiments, the appliance may evaluate an object-orientedexpression 610. In some embodiments, the appliance may determine aboolean value corresponding to the rule.

In response to the evaluation of the rule 605, the appliance processesthe identified second policy group (step 1107). In some embodiments, theappliance may only process the second policy group if the rule evaluatesto true. In other embodiments, the appliance may only process the secondpolicy group if the rule evaluates to a non-zero value. The appliancemay process the second group in any manner. In some embodiments, theappliance may process the second policy bank beginning with a specificpolicy identified by an invocation action 1110.

In some embodiments, after processing the second policy group, theappliance may process a second policy of the first policy group. Forexample, in FIG. 11A, an appliance may evaluate the policy of line 11 inthe policy bank 1000 b. If the rule is true, the appliance may take theinvocation action 1110, and the appliance may process policy bank 1000c. After completing the processing of policy bank P3, the appliance mayreturn to the policy bank 1000 b and process the next instruction, whichis line 12. In some embodiments, the appliance may only resumeprocessing the first policy bank if the second policy bank results in asoft stop, such as where the last instruction of a policy bank points aNEXT instruction, as in line 30 of policy bank 1000 c. In otherembodiments, the appliance may resume processing of the first policybank even where a hard stop is indicated, such as line 11 of policy bank1000 c.

In some embodiments, the second policy group may also contain one ormore invocation actions. In these embodiments, policy bank evaluationsmay be chained in any manner. In some embodiments, an appliance 200 mayprocess a third policy group, where the third policy group is identifiedby a policy 600 in the second policy group. In other embodiments, thefirst policy bank may have a plurality of invocation actions 1110. Inthese embodiments, the appliance may process a third policy group, wherethe third policy group is identified by a second policy 600 of the firstpolicy group. In still other embodiments, the first policy 600 specifiesa second policy 600 of the first policy group to be processed after thesecond policy group is processed. For example, a policy comprising aninvocation action 1110 may also comprise a flow instruction whichspecifies a policy of the first policy group to be processed afterprocessing returns from the second policy group.

G. Systems and Methods for Configuring and Using Application SecurityProfiles

Referring now to FIG. 12, a number of configuration screens 1200, 1210,1260, 1240 for configuring an application security profile are shown. Inbrief overview, a profile creation screen 1200 allows a user to input aname and general properties for a new application security profile. Aprofile configuration screen 1210 allows a user to select one or morechecks contained within a profile. Two check configuration screens 1240,1260 may then allow a user to modify settings of an individual check.

Still referring to FIG. 12, now in greater detail, a creation screen1200 allows a user to input a profile name and additional informationrelating to the profile. A profile may be named in any manner. In someembodiments, a profile name may reflect the function or functions of theprofile. Any additional information may be specified along with theprofile. In one embodiment, the profile may specify information aboutthe type of network traffic the profile applies to. For example, theprofile may apply to HTTP or HTML traffic. Or the profile may apply towebservices traffic.

A profile configuration screen 1210 may allow a user to specify one ormore checks to use with the profile. A check may comprise any set ofpolicies or actions related to a common security function. For example,a cookie check may comprise a set of policies, settings or actions toprevent cookie tampering. Or a credit card check may comprise a set ofpolicies, settings, or actions to prevent against confidential creditcard information being transmitted via a device. In the embodimentshown, a user is given a choice to block, alert or log with respect to agiven check. If “block” is selected, the profile may block all trafficwhich does not satisfy the check. If “alert” is selected, anadministrator or user may receive an alert if a packet stream does notsatisfy the check. If “log” is selected, a log entry may be created eachtime a packet stream is transmitted through a device that does notcomply with the check. The profile configuration screen may provide theoption to modify any of these checks and rules. In some embodiment, anymodifications to a check may be translated into an underlying policyexpression used to configure a network device.

A check configuration screen 1240, 1260 may comprise any input means formodifying a check. In one embodiment, a user may be able to specify oneor more policies to be included in a check. In another embodiment, auser may be able to modify one or more settings of the check. A settingof a check may comprise any information used by the check in determiningwhether a traffic stream satisfies the check. For example, with respectto a check that validates starting URLs, a setting may comprise one ormore allowed starting URLs. Or for example, for a form field formatcheck, a setting may comprise one or more addresses for which the formatcheck should be applied. In some embodiments a setting may correspond toone or more elements of an underlying policy. For example, an allowedstarting URL may be incorporated as an expression in the rule of apolicy having an action that allows the traffic to pass.

Referring now to FIG. 13A, a flow diagram of a method for configuringone or more application security profiles for a device, where eachapplication security profile specifies a number of checks to performsecurity functions related to an application is shown. In briefoverview, the method comprises providing a configuration interface forconfiguring an application security profile (step 1301). The methodcomprises receives a first setting, via the configuration interface,which corresponds to a first check of the application security profile(step 1303). The method also comprises receiving, via the configurationinterface, a second setting, which corresponds to a second check of theapplication security profile (step 1305). The method also comprisesidentifying a policy 600 that specifies a rule 605 that includes a firstexpression 600 (step 1307). The method may then comprise receivinginformation identifying an application security profile to be processedbased on an evaluation of the rule 605 (step 1309).

Still referring to FIG. 13A, now in further detail, a configurationinterface is provided for configuring an application security profile(step 1301). The configuration interface may comprise any configurationinterfaces, components, and methods described herein. In someembodiments, the configuration interface comprises one or more of adrag-and-drop interface, a list-selection interface, or asyntax-highlighting interface. In other embodiments, the configurationinterface may comprise an expression configuration screen 600. In stillother embodiments, the configuration interface may comprise any numberof profile creation screens 1300, check configuration screens 1310,and/or setting configuration screens 1340, 1360. In still otherembodiments, the configuration interface 700 is a command lineinterface. The configuration interface may execute on any device. Insome embodiments, the method includes executing the configurationinterface 700 on a device in communication with a network device 200. Inother embodiments, the method includes executing the configurationinterface 700 on the network device 200. In one embodiment, the methodprovides a user with a configuration interface 1300 for creating aplurality of application profiles.

A device may receive, via a configuration interface, a first settingthat specifies a corresponding first check of the application securityprofile (step 1303). In some embodiments, the device receives from theconfiguration interface 700 a URL to be used by the first check. Inother embodiments, the device receives from the configuration interface700 an expression 610 specifying one or more URLs to be used by thefirst check. In still other embodiments, the device receives from theconfiguration interface 700 an object-oriented expression 600 specifyingone or more URLs to be used by the first check. In some embodiments, thesetting may comprise an indication whether the check should block, log,or generate an alert with respect to a packet stream that violates thecheck. In other embodiments, the setting may comprise an element of oneor more policies included in the check.

The device also receives, via the configuration interface 700, a secondsetting that specifies a corresponding second check of the applicationsecurity profile (step 1305 This setting may be received in any manner,including any manner in which the first setting was received.

The device may identify, via the configuration interface 700, a policy600 that specifies a rule 605 which includes a first expression 610(step 1307). In some embodiments, the policy may comprise anobject-oriented expression. The policy may be identified in any manner.In some embodiments, the policy may be chosen from a list. In otherembodiments, the policy may be chosen via a drag-and-drop interface. Instill other embodiments, the policy may be automatically chosen withrespect to a given profile. In one embodiment, the policy may be inputdirectly by a user.

The device may receive, via the interface 700, information thatidentifies the application security profile to be processed based on anevaluation of the rule 605 (step 1309). In one embodiment, theapplication security profile may be represented as a policy bank, and aninvocation action may be added to the policy identifying the policybank. In some embodiments, the method includes storing the applicationsecurity profile. In other embodiments, the method includes transmittingthe application security profile to a network device 200.

In some embodiments, an application security profile may be specified asan action for more than one policies. For example, there may be severalconditions under which an application security profile including formfield consistency and buffer overflow checks should be applied. Aplurality of policies, each specifying one of the several conditions,each may invoke the application security profile as an action.

Referring now to FIG. 13B, an embodiment of a method for executing oneor more application security profiles for a device, each applicationsecurity profile specifying a number of policy groups performingsecurity functions related to an application is shown. In briefoverview, the method includes an appliance identifying a first policy toapply to a received packet stream; where the first policy 600 specifiesa rule 605 that includes a first expression 610 and identifies anapplication security profile (step 1321). The appliance 200 evaluatesthe rule 605 (step 1323). The appliance, in response to the evaluationof the rule 605, processes a first check specified by the applicationsecurity profile (step 1325). In response to the evaluation of the rule605, the appliance also processes a second check specified by theapplication security profile (step 1327).

Still referring to FIG. 13B, now in further detail, the method includesan appliance to identify a first policy to apply to a received packetstream; where the first policy 600 specifies a rule 605 that includes afirst expression 610 and identifies an application security profile(step 1321). In some embodiments, the appliance 200 comprises a VPNproxy device. In some other embodiments, the appliance 200 identifies afirst policy 600 to apply to a received TCP packet stream. The packetstream may be received in any manner and from any source. The packetstream may comprise any protocol or protocols.

The appliance 200 evaluates the rule of the policy (step 1323). Theappliance may evaluate the rule according any to technique. In someembodiments, the rule may comprise an object-oriented expression. Inother embodiments, the rule may comprise a plurality of object orientedexpressions. In some embodiments, the appliance may determine a booleanvalue as a result of evaluating the expression.

In response to the evaluation of the rule 605, the appliance 200processes a first check specified by the application security profile(step 1325). In some embodiments, the appliance may process the firstcheck in response to determining that the rule is true.

The appliance may process the first check in any manner. In someembodiments, the appliance evaluates at least one setting of the firstcheck to determine whether to apply the first check. In some otherembodiments, the appliance determines that a URL contained in the packetstream matches at least one setting of the first check, and applies thefirst check in response to the determination. In still otherembodiments, the appliance may determine that a URL contained in thepacket stream matches an expression 610 of one setting of the firstcheck, and applying the first check in response to the determination. Inother embodiments, the appliance may determine that a URL contained inthe packet stream matches an object-oriented expression 610 of onesetting of the first check. The appliance may apply the first check inresponse to the determination.

Also in response to the evaluation of the rule 605, the appliance 200may process a second check specified by the application security profile(step 1327). In some embodiments, the appliance may process the secondcheck in response to determining that the rule is true. In someembodiments, the method uses at least one of the first check and secondcheck in order to perform one of: SQL injection detection, invalidstarting URL detection, cookie tampering detection, form fieldconsistency detection, buffer overflow detection, cross-site scriptingdetection, credit card number detection, and invalid URL detection. Insome other embodiments, the method uses at least one of the first checkand second check to perform one of: SQL injection blocking, invalidstarting URL blocking, cookie tampering blocking, inconsistent formfield blocking, buffer overflow blocking, cross-site scripting blocking,credit card number blocking, and invalid URL blocking.

While the invention has been particularly shown and described withreference to specific preferred embodiments, it should be understood bythose skilled in the art that various changes in form and detail may bemade therein without departing from the spirit and scope of theinvention as defined by the appended claims.

1. A method of configuring a network device to specify flow controlamong policies used in processing a packet stream, the methodcomprising: (a) providing a configuration interface for configuring aplurality of policies of a network device, at least one policy of theplurality of policies comprising a policy identifier; and (b) receiving,via the configuration interface, information identifying a first policyof the plurality of policies, the first policy identifying (i) a rulecomprising a first expression and (ii) a first action to be taken basedon an evaluation of the rule; and (c) receiving, via the configurationinterface, information identifying a second policy of the plurality ofpolicies to apply subsequent to the first policy if the rule evaluatesto true.
 2. The method of claim 1, wherein step (a) comprises providinga command-line configuration interface.
 3. The method of claim 1,wherein step (a) comprises providing a configuration interfacecomprising one or more of a drag-and-drop interface, a list-selectioninterface, or a syntax-highlighting interface.
 4. The method of claim 1,wherein step (a) comprises executing the configuration interface on adevice in communication with the network device.
 5. The method of claim1, wherein step (a) comprises executing the configuration interface onthe network device.
 6. The method of claim 1, wherein the firstexpression is an object-oriented expression.
 7. The method of claim 1,wherein the first action comprises no action.
 8. The method of claim 1,wherein the first action specifies a function performing one of: loadbalancing, content switching, application security, applicationdelivery, network acceleration, or application acceleration.
 9. Themethod of claim 1, wherein step (c) comprises receiving an integerspecifying a line number of a second policy.
 10. The method of claim 1,wherein step (c) comprises receiving an policy identifier specifying asecond policy.
 11. The method of claim 1, wherein step (c) comprisesreceiving an expression to be evaluated at runtime to specify a linenumber of a second policy.
 12. The method of claim 1, wherein step (c)comprises receiving an object-oriented expression to be evaluated atruntime to specify a line number of a second policy.
 13. The method ofclaim 1, wherein the plurality of policies comprises a policy bank. 14.The method of claim 1, wherein each policy of the plurality of policiescomprises a ranking indicating a default order in which the policieswill be processed by a network device.
 15. A method of flow controlamong policies used in a network device processing a packet stream, themethod comprising: (a) identifying, by an appliance, a plurality ofpolicies to apply to a received packet stream, at least one policy ofthe plurality of policies comprising a policy identifier; (b)processing, by the appliance, a first policy of the plurality ofpolicies, the first policy identifying (i) a rule comprising a firstexpression and (ii) a first action to be taken based on an evaluation ofthe rule, and (iii) a second policy of the plurality of policies; (c)determining, by the appliance based on an evaluation of the expression,the rule evaluates to true; and (d) processing, by the appliance inresponse to the determination, the identified second policy.
 16. Themethod of claim 15, wherein step (c) comprises evaluating anobject-oriented expression.
 17. The method of claim 15, furthercomprising the step of performing, in response to the determination, anaction identified by the first policy.
 18. The method of claim 15,further comprising the step of executing, in response to thedetermination, an action identified by the first policy; the actioncomprising performing one of: load balancing, content switching,application security, application delivery, network acceleration, orapplication acceleration.
 19. The method of claim 15, wherein the firstpolicy comprises an integer specifying a ranking of a second policy ofthe plurality of policies to be processed next if the first actionapplies.
 20. The method of claim 15, wherein step (d) comprisesevaluating, by the appliance, an expression to determine a ranking of asecond policy of the plurality of policies to be processed next.
 21. Themethod of claim 15, wherein step (d) comprises evaluating, by theappliance, an object oriented expression to determine a ranking of asecond policy of the plurality of policies to be processed next.
 22. Themethod of claim 15, wherein the plurality of policies comprises a policybank.
 23. The method of claim 15, wherein each policy of the pluralityof policies comprises a ranking indicating a default order in which thepolicies should be processed.
 24. The method of claim 15, furthercomprising storing in a list, in response to the determination, anaction identified by the first policy.
 25. The method of claim 24,further comprising storing, in the list, at least one other action, theat least one other action identified in at least one other policy havinga rule evaluated to true.
 26. The method of claim 25 further comprisingperforming each action stored in the list of actions.
 27. An applianceproviding flow control among policies used in a network deviceprocessing a packet stream, the appliance comprising: a packet processorwhich receives a packet stream; and a policy engine which identifies aplurality of policies to apply to a received packet stream, at least onepolicy of the plurality of policies comprising a policy identifier;processes a first policy of the plurality of policies, the first policyidentifying (i) a rule comprising a first expression and (ii) a firstaction to be taken based on an evaluation of the rule, and (iii) asecond policy of the plurality of policies; determines, based on anevaluation of the expression, the rule evaluates to true; and processes,by the appliance in response to the determination, the identified secondpolicy.
 28. The system of claim 27, wherein the policy engine evaluatesan object-oriented expression.
 29. The system of claim 27, wherein thepolicy engine performs, in response to the determination, an actionidentified by the first policy.
 30. The system of claim 27, wherein thepolicy engine performs, in response to the determination, an actionidentified by the first policy; the action comprising performing one of:load balancing, content switching, application security, applicationdelivery, network acceleration, or application acceleration.
 31. Thesystem of claim 27, wherein the first policy comprises an integerspecifying a ranking of a second policy of the plurality of policies tobe processed next if the first action applies.
 32. The system of claim27, wherein the policy engine evaluates an expression to determine aranking of a second policy of the plurality of policies to be processednext.
 33. The system of claim 27, wherein the policy engine evaluates anobject oriented expression to determine a ranking of a second policy ofthe plurality of policies to be processed next.
 34. The system of claim27, wherein the plurality of policies comprises a policy bank.
 35. Thesystem of claim 27, wherein each policy of the plurality of policiescomprises a ranking indicating a default order in which the policiesshould be processed.
 36. The system of claim 27, wherein the policyengine stores in a list, in response to the determination, an actionidentified by the first policy.
 37. The system of claim 36, wherein thepolicy engine stores, in the list, at least one other action, the atleast one other action identified in at least one other policy having arule evaluated to true.
 38. The system of claim 37, wherein the policyengine performs each action stored in the list of actions.